diff --git a/server/src/bin.rs b/server/src/bin.rs
index 6db5da5e..9dc1e529 100644
--- a/server/src/bin.rs
+++ b/server/src/bin.rs
@@ -1,6 +1,9 @@
+#[macro_use] extern crate log;
+
 use std::{
     path::{Path, PathBuf},
     env,
+    process,
 };
 
 use clap::clap_app;
@@ -73,9 +76,16 @@ fn main() {
             let options = commands::BuildOptions {
                 fuzzy_project_path,
                 output_file,
+                output_kind: None, // TODO: Accept from argument
             };
 
-            commands::build(&options);
+            match commands::build(&options) {
+                Ok(_) => {},
+                Err(e) => {
+                    error!("{}", e);
+                    process::exit(1);
+                },
+            }
         },
         _ => {
             app.print_help().expect("Could not print help text to stdout!");
diff --git a/server/src/commands/build.rs b/server/src/commands/build.rs
index d3e81fa2..9ac990f0 100644
--- a/server/src/commands/build.rs
+++ b/server/src/commands/build.rs
@@ -1,33 +1,76 @@
 use std::{
     path::PathBuf,
     fs::File,
-    process,
+    fmt,
 };
 
 use rbxmx;
 
 use crate::{
     rbx_session::construct_oneoff_tree,
-    project::Project,
+    project::{Project, ProjectLoadFuzzyError},
     imfs::Imfs,
 };
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OutputKind {
+    Rbxmx,
+    Rbxlx,
+}
+
+fn detect_output_kind(options: &BuildOptions) -> Option<OutputKind> {
+    match options.output_kind {
+        Some(output_kind) => Some(output_kind),
+        None => {
+            let extension = options.output_file.extension()?.to_str()?;
+
+            match extension {
+                "rbxlx" => Some(OutputKind::Rbxlx),
+                "rbxmx" => Some(OutputKind::Rbxmx),
+                _ => None,
+            }
+        },
+    }
+}
+
 #[derive(Debug)]
 pub struct BuildOptions {
     pub fuzzy_project_path: PathBuf,
     pub output_file: PathBuf,
+    pub output_kind: Option<OutputKind>,
 }
 
-pub fn build(options: &BuildOptions) {
+pub enum BuildError {
+    UnknownOutputKind,
+    ProjectLoadError(ProjectLoadFuzzyError),
+}
+
+impl fmt::Display for BuildError {
+    fn fmt(&self, output: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            BuildError::UnknownOutputKind => {
+                write!(output, "Could not detect what kind of output file to create")
+            },
+            BuildError::ProjectLoadError(inner) => write!(output, "{}", inner),
+        }
+    }
+}
+
+impl From<ProjectLoadFuzzyError> for BuildError {
+    fn from(error: ProjectLoadFuzzyError) -> BuildError {
+        BuildError::ProjectLoadError(error)
+    }
+}
+
+pub fn build(options: &BuildOptions) -> Result<(), BuildError> {
+    let output_kind = detect_output_kind(options)
+        .ok_or(BuildError::UnknownOutputKind)?;
+
+    info!("Hoping to generate file of type {:?}", output_kind);
+
     info!("Looking for project at {}", options.fuzzy_project_path.display());
 
-    let project = match Project::load_fuzzy(&options.fuzzy_project_path) {
-        Ok(project) => project,
-        Err(error) => {
-            error!("{}", error);
-            process::exit(1);
-        },
-    };
+    let project = Project::load_fuzzy(&options.fuzzy_project_path)?;
 
     info!("Found project at {}", project.file_location.display());
     info!("Using project {:#?}", project);
@@ -36,10 +79,21 @@ pub fn build(options: &BuildOptions) {
         .expect("Could not create in-memory filesystem");
 
     let tree = construct_oneoff_tree(&project, &imfs);
-    let root_id = tree.get_root_id();
 
     let mut file = File::create(&options.output_file)
         .expect("Could not open output file for write");
 
-    rbxmx::encode(&tree, &[root_id], &mut file);
+    match output_kind {
+        OutputKind::Rbxmx => {
+            let root_id = tree.get_root_id();
+            rbxmx::encode(&tree, &[root_id], &mut file);
+        },
+        OutputKind::Rbxlx => {
+            let root_id = tree.get_root_id();
+            let top_level_ids = tree.get_instance(root_id).unwrap().get_children_ids();
+            rbxmx::encode(&tree, top_level_ids, &mut file);
+        },
+    }
+
+    Ok(())
 }
\ No newline at end of file