diff --git a/.gitignore b/.gitignore
index 6dd29b7..44f3e23 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-bin/
\ No newline at end of file
+bin/
+build
\ No newline at end of file
diff --git a/Makefile b/Makefile
deleted file mode 100644
index 0923e9f..0000000
--- a/Makefile
+++ /dev/null
@@ -1,27 +0,0 @@
-all: clean build
-
-clean:
-	rm -rf bin/
-
-# The following settings are very important!
-# -c arduino for flashing to an AVR device with arduino bootloader.
-# -p atmega328p is for the specific microcontroller.
-# -b 57600 is the baudrate for transmission. Nano boards ONLY accept 57600, uno boards might accept 115200.
-# -P specifies the port.
-flash: build
-	avrdude -c arduino -p atmega328p -P /dev/ttyUSB0 -b 57600 -U flash:w:bin/gympal.hex:i
-
-build: gympal.hex
-
-gympal.hex: gympal.o control.o
-	avr-gcc -Os -mmcu=atmega328p -o bin/gympal.elf bin/gympal.o bin/control.o
-	avr-objcopy -O ihex -R .eeprom bin/gympal.elf bin/gympal.hex
-
-gympal.o: src/gympal.c bin
-	avr-gcc -Wall -Os -DF_CPU=16000000UL -mmcu=atmega328p -c -o bin/gympal.o src/gympal.c
-
-control.o: src/control.c bin
-	avr-gcc -Wall -Os -DF_CPU=16000000UL -mmcu=atmega328p -c -o bin/control.o src/control.c
-
-bin:
-	mkdir bin
\ No newline at end of file
diff --git a/README.md b/README.md
index f89e940..c350381 100644
--- a/README.md
+++ b/README.md
@@ -6,9 +6,13 @@ The GymPal is a lightweight piece of hardware with built-in storage, time-keepin
 ## Development
 The software for this system is developed in C, using [avr-libc](https://www.nongnu.org/avr-libc/), and the build toolchain is managed by make, using [avr-gcc](https://linux.die.net/man/1/avr-gcc) and [avr-dude](https://github.com/avrdudes/avrdude) to upload firmware to the Atmega328p microcontroller.
 
-To compile the firmware, you can run `make`.
+```shell
+sudo apt install gcc-avr
+sudo apt install avr-libc
+sudo apt install avrdude
+```
 
-To upload the firmware to an Arduino, run `make flash`.
+After cloning this repository, you must first compile the build script with `./prepare-build-tools.d`. Then, you can run `./build <command>` to run various build commands. See `./build help` for more information.
 
 ## Hardware
 Here's a list of the hardware that this project uses, just for reference:
diff --git a/build-tools/README.md b/build-tools/README.md
new file mode 100644
index 0000000..725d415
--- /dev/null
+++ b/build-tools/README.md
@@ -0,0 +1,4 @@
+# Build-Tools
+This directory contains the sources for a small D program that manages compilation and uploading of code to AVR devices.
+
+Run `./prepare-build-tools.d` from the main project directory to compile it.
diff --git a/build.d b/build-tools/build.d
similarity index 57%
rename from build.d
rename to build-tools/build.d
index e7311bc..49eb195 100755
--- a/build.d
+++ b/build-tools/build.d
@@ -9,13 +9,9 @@ import std.file;
 import std.string;
 import std.conv;
 import std.path;
-import std.digest.md;
-import std.base64;
 
-const string MCU_ID = "atmega328p";
-const ulong CPU_FREQ = 16_000_000;
-const string BOOTLOADER = "arduino";
-const ulong AVRDUDE_BAUDRATE = 57_600;
+import util;
+import hash;
 
 const string SOURCE_DIR = "src";
 const string BUILD_DIR = "bin";
@@ -28,12 +24,20 @@ const string[] COMPILER_FLAGS = [
     "-mmcu=atmega328p"
 ];
 
+const string[] AVRDUDE_FLAGS = [
+    "-c arduino",
+    "-p m328p",
+    "-P /dev/ttyUSB0",
+    "-b 57600",
+    "-u"
+];
+
 alias BuildCommand = int function(string[]);
 
 int main(string[] args) {
     string command;
     if (args.length < 2) {
-        command = "help";
+        command = "build";
     } else {
         command = args[1].strip.toLower;
     }
@@ -57,16 +61,21 @@ int main(string[] args) {
 
 int helpCommand(string[] args) {
     writeln("build.d - A simple build script for C files.");
+    writeln("--------------------------------------------");
+    writeln("Usage: ./build.d <command> [args...]");
+    writeln("");
     writeln("The following commands are available:");
-    writeln("build [-f] - Compiles source code. Use -f to force rebuild.");
-    writeln("  By default, sources are hashed, and only built if changes are detected.");
-    writeln("flash [buildArgs] - Flashes code onto a connected AVR device via AVRDude.");
-    writeln("clean - Removes all build files.");
-    writeln("help - Shows this help information.");
+    writeln("  build [-f]    Compiles source code. Use -f to force rebuild.");
+    writeln("                By default, sources are hashed, and only built if changes are detected.");
+    writeln("                This is also the default command if none is specified.");
+    writeln("  flash         Flashes code onto a connected AVR device via AVRDude.");
+    writeln("  clean         Removes all build files.");
+    writeln("  help          Shows this help information.");
     return 0;
 }
 
 int clean(string[] args) {
+    if (!exists(BUILD_DIR)) return 0;
     rmdirRecurse(BUILD_DIR);
     return 0;
 }
@@ -77,9 +86,16 @@ int buildCommand(string[] args) {
 }
 
 int flashCommand(string[] args) {
-    int result = buildCommand(args);
-    if (result != 0) return result;
-    return flashToMCU(buildPath("bin", "gympal.hex"));
+    string hexFilePath = buildPath(BUILD_DIR, "gympal.hex");
+    if (!exists(hexFilePath)) {
+        writeln("Hex file doesn't exist yet; building it now.");
+        int result = buildCommand(args);
+        if (result != 0) return result;
+    }
+    string flags = join(AVRDUDE_FLAGS, " ");
+    string cmd = format!"avrdude %s -U flash:w:%s:i"(flags, hexFilePath);
+    writeln(cmd);
+    return run(cmd);
 }
 
 int build(bool force = false) {
@@ -101,35 +117,8 @@ int build(bool force = false) {
     return 0;
 }
 
-//-------- Utility functions below here -------
-
-int run(string shellCommand) {
-    import std.process : Pid, spawnShell, wait;
-    Pid pid = spawnShell(shellCommand);
-    return wait(pid);
-}
-
-void runOrQuit(string shellCommand, int[] successExitCodes = [0]) {
-    import core.stdc.stdlib : exit;
-    import std.algorithm : canFind;
-    int result = run(shellCommand);
-    if (!canFind(successExitCodes, result)) exit(result);
-}
-
-void quitIfNonZero(int n) {
-    import core.stdc.stdlib : exit;
-    if (n != 0) exit(n);
-}
-
 bool shouldCompileSource(string sourcePath) {
-    string name = baseName(sourcePath);
-    name = name[0 .. name.lastIndexOf('.')];
-    string hashPath = buildPath("bin", "hash", name ~ ".md5");
-    string objectPath = buildPath("bin", name ~ ".o");
-    if (!exists(hashPath) || !exists(objectPath)) return true;
-    ubyte[] storedHash = Base64.decode(readText(hashPath).strip());
-    ubyte[16] currentHash = md5Of(readText(sourcePath));
-    return storedHash != currentHash;
+    return !contentMatchesHash(sourcePath);
 }
 
 string compileSourceToObject(string sourcePath, bool force = false) {
@@ -137,7 +126,6 @@ string compileSourceToObject(string sourcePath, bool force = false) {
     string name = baseName(sourcePath);
     name = name[0 .. name.lastIndexOf('.')];
     string objectPath = buildPath("bin", name ~ ".o");
-    string hashPath = buildPath("bin", "hash", name ~ ".md5");
 
     if (!force && !shouldCompileSource(sourcePath)) {
         writefln!"Not compiling %s because no changes detected."(sourcePath);
@@ -151,12 +139,7 @@ string compileSourceToObject(string sourcePath, bool force = false) {
     );
     writeln(cmd);
     runOrQuit(cmd);
-
-    ubyte[16] hash = md5Of(readText(sourcePath));
-    string hashDir = buildPath("bin", "hash");
-    if (!exists(hashDir)) mkdir(hashDir);
-    std.file.write(hashPath, Base64.encode(hash));
-
+    saveHash(sourcePath);
     return objectPath;
 }
 
@@ -184,25 +167,3 @@ string copyToHex(string elfFile) {
     runOrQuit(cmd);
     return hexFile;
 }
-
-int flashToMCU(string hexFile) {
-    string cmd = format!"avrdude -c %s -p m328p -P /dev/ttyUSB0 -b %d -u -U flash:w:%s:i"(
-        BOOTLOADER,
-        AVRDUDE_BAUDRATE,
-        hexFile
-    );
-    writeln(cmd);
-    return run(cmd);
-}
-
-string[] findFiles(string path, string suffix = null) {
-    import std.array;
-    import std.algorithm;
-    auto app = appender!(string[]);
-    foreach (DirEntry entry; dirEntries(path, SpanMode.breadth, false)) {
-        if (entry.isFile && (suffix is null || entry.name.endsWith(suffix))) {
-            app ~= entry.name;
-        }
-    }
-    return app[];
-}
diff --git a/build-tools/hash.d b/build-tools/hash.d
new file mode 100644
index 0000000..fc4fdf5
--- /dev/null
+++ b/build-tools/hash.d
@@ -0,0 +1,65 @@
+/** 
+ * Helper for hashing the content of source files to determine if we need to
+ * re-compile certain sources.
+ */
+module hash;
+
+import std.stdio;
+import std.file;
+import std.string;
+import std.digest.md;
+import std.base64;
+
+const HASH_FILE = "bin/hash.txt";
+
+/** 
+ * Determines if the content of the source file at the given path matches
+ * the hash we have for it (if possible).
+ * Params:
+ *   sourcePath = The path to the source file.
+ * Returns: True if we have a hash for the source file, and it matches the
+ * current hash of the file contents. False if we don't have a hash or it
+ * doesn't match.
+ */
+bool contentMatchesHash(string sourcePath) {
+    if (!exists(sourcePath) || !isFile(sourcePath)) return false;
+    string[string] hashes = readHashes();
+    if (sourcePath !in hashes) return false;
+    ubyte[16] rawHash = md5Of(readText(sourcePath));
+    ubyte[] savedHash = Base64.decode(hashes[sourcePath]);
+    return rawHash == savedHash;
+}
+
+/** 
+ * Saves the hash of the given source path to the hash file.
+ * Params:
+ *   sourcePath = The source path of the file to save.
+ */
+void saveHash(string sourcePath) {
+    if (!exists(sourcePath) || !isFile(sourcePath)) return;
+    ubyte[16] rawHash = md5Of(readText(sourcePath));
+    string hash = Base64.encode(rawHash);
+    string[string] hashes = readHashes();
+    hashes[sourcePath] = hash;
+    saveHashes(hashes);
+}
+
+private string[string] readHashes() {
+    string[string] hashes;
+    if (!exists(HASH_FILE)) return hashes;
+    auto file = File(HASH_FILE, "r");
+    foreach (string line; lines(file)) {
+        string[] parts = split(line, ":");
+        string sourcePath = parts[0].strip;
+        string hashBase64 = parts[1].strip;
+        hashes[sourcePath] = hashBase64;
+    }
+    return hashes;
+}
+
+private void saveHashes(string[string] hashes) {
+    auto file = File(HASH_FILE, "w");
+    foreach (string sourcePath, string hash; hashes) {
+        file.writefln!"%s:%s"(sourcePath, hash);
+    }
+}
\ No newline at end of file
diff --git a/build-tools/util.d b/build-tools/util.d
new file mode 100644
index 0000000..42022f7
--- /dev/null
+++ b/build-tools/util.d
@@ -0,0 +1,56 @@
+module util;
+
+/** 
+ * Runs the given shell command.
+ * Params:
+ *   shellCommand = The command to run.
+ * Returns: The exit code of the command.
+ */
+int run(string shellCommand) {
+    import std.process : Pid, spawnShell, wait;
+    Pid pid = spawnShell(shellCommand);
+    return wait(pid);
+}
+
+/** 
+ * Runs the given command, and exits if an unsatisfactory exit code is returned.
+ * Params:
+ *   shellCommand = The command to run.
+ *   successExitCodes = The list of exit codes which are considered success.
+ */
+void runOrQuit(string shellCommand, int[] successExitCodes = [0]) {
+    import core.stdc.stdlib : exit;
+    import std.algorithm : canFind;
+    int result = run(shellCommand);
+    if (!canFind(successExitCodes, result)) exit(result);
+}
+
+/** 
+ * Exits the program if the given number is non-zero.
+ * Params:
+ *   n = The number to check.
+ */
+void quitIfNonZero(int n) {
+    import core.stdc.stdlib : exit;
+    if (n != 0) exit(n);
+}
+
+/** 
+ * Finds a list of files in a directory which match a given suffix.
+ * Params:
+ *   path = The path to look in.
+ *   suffix = The suffix to match.
+ * Returns: The list of paths to files that match.
+ */
+string[] findFiles(string path, string suffix = null) {
+    import std.array;
+    import std.algorithm;
+    import std.file;
+    auto app = appender!(string[]);
+    foreach (DirEntry entry; dirEntries(path, SpanMode.breadth, false)) {
+        if (entry.isFile && (suffix is null || entry.name.endsWith(suffix))) {
+            app ~= entry.name;
+        }
+    }
+    return app[];
+}
\ No newline at end of file
diff --git a/prepare-build-tools.d b/prepare-build-tools.d
new file mode 100755
index 0000000..1b01249
--- /dev/null
+++ b/prepare-build-tools.d
@@ -0,0 +1,29 @@
+#!/usr/bin/env rdmd
+/**
+ * Simple script that just compiles this project's build system to an executable.
+ * Run this before building: `./prepare-build-tools.d`
+ */
+module prepare_build_tools;
+
+import std.process;
+import std.array;
+import std.file;
+import std.algorithm;
+
+int main() {
+    auto sourceApp = appender!(string[]);
+    foreach (DirEntry entry; dirEntries("build-tools", SpanMode.shallow, false)) {
+        if (entry.isFile && endsWith(entry.name, ".d")) {
+            sourceApp ~= entry.name;
+        }
+    }
+    string[] sources = sourceApp[];
+    string sourcesStr = join(sources, " ");
+    Pid pid = spawnShell("dmd -O " ~ sourcesStr ~ " -release -of=build");
+    scope (exit) {
+        if (exists("build.o")) {
+            std.file.remove("build.o");
+        }
+    }
+    return wait(pid);
+}
diff --git a/src/display.c b/src/display.c
index 2451c90..7e14984 100644
--- a/src/display.c
+++ b/src/display.c
@@ -1,5 +1,6 @@
 #include "display.h"
 
+// Chip Select
 struct signal cs = { .ddr = &DDRB, .port = &PORTB, .pin = 2 };
 // Back Light
 struct signal bl = { .ddr = &DDRB, .port = &PORTB, .pin = 1 };
diff --git a/src/display.h b/src/display.h
index 2505322..d272fda 100644
--- a/src/display.h
+++ b/src/display.h
@@ -7,13 +7,18 @@
 #ifndef DISPLAY_H
 #define DISPLAY_H
 
-#include "st7735.h"
+#include "lib/st7735.h"
 
 /**
  * @brief Initializes the display.
  */
 void display_init();
 
+/**
+ * @brief Gets a pointer to the underlying ST7735 LCD struct, which can be used
+ * for calling functions on it manually.
+ * @return A pointer to the ST7735 LCD struct.
+ */
 struct st7735* display_get_lcd();
 
 void display_show_str(char* str);
diff --git a/src/lib/ds3231.c b/src/lib/ds3231.c
new file mode 100644
index 0000000..3968297
--- /dev/null
+++ b/src/lib/ds3231.c
@@ -0,0 +1,3 @@
+#include "ds3231.h"
+
+// TODO: Implement this!
\ No newline at end of file
diff --git a/src/lib/ds3231.h b/src/lib/ds3231.h
new file mode 100644
index 0000000..a0cd63c
--- /dev/null
+++ b/src/lib/ds3231.h
@@ -0,0 +1,8 @@
+#ifndef DS3231_H
+#define DS3231_H
+
+// TODO: Implement this!
+
+void ds3231_init();
+
+#endif
\ No newline at end of file
diff --git a/src/font.c b/src/lib/font.c
similarity index 100%
rename from src/font.c
rename to src/lib/font.c
diff --git a/src/font.h b/src/lib/font.h
similarity index 100%
rename from src/font.h
rename to src/lib/font.h
diff --git a/src/st7735.c b/src/lib/st7735.c
similarity index 100%
rename from src/st7735.c
rename to src/lib/st7735.c
diff --git a/src/st7735.h b/src/lib/st7735.h
similarity index 100%
rename from src/st7735.h
rename to src/lib/st7735.h