diff --git a/MetaballsKit/Renderer.swift b/MetaballsKit/Renderer.swift
index edc7684..3c5214a 100644
--- a/MetaballsKit/Renderer.swift
+++ b/MetaballsKit/Renderer.swift
@@ -25,59 +25,75 @@ struct Vertex {
 }
 
 public class Renderer: NSObject, MTKViewDelegate {
-    var delegate: RendererDelegate
+    public var delegate: RendererDelegate? = nil {
+        didSet {
+            guard let delegate = delegate else {
+                return
+            }
+
+            let view = delegate.metalView
+            view.device = device
+
+            do {
+                let library = try device.makeDefaultLibrary(bundle: Bundle.main)
+                let vertexShader = library.makeFunction(name: "passthroughVertexShader")
+                let fragmentShader = library.makeFunction(name: "sampleToColorShader")
+
+                let pipelineStateDescriptor = MTLRenderPipelineDescriptor()
+                pipelineStateDescriptor.label = "Render Pipeline"
+                pipelineStateDescriptor.vertexFunction = vertexShader
+                pipelineStateDescriptor.fragmentFunction = fragmentShader
+                if let renderAttachment = pipelineStateDescriptor.colorAttachments[0] {
+                    renderAttachment.pixelFormat = view.colorPixelFormat
+                    // Pulled all this from SO. I don't know what all this does...
+                    // https://stackoverflow.com/q/43727335/1174185
+                    renderAttachment.isBlendingEnabled = true
+                    renderAttachment.alphaBlendOperation = .add
+                    renderAttachment.rgbBlendOperation = .add
+                    renderAttachment.sourceRGBBlendFactor = .sourceAlpha
+                    renderAttachment.sourceAlphaBlendFactor = .sourceAlpha
+                    renderAttachment.destinationRGBBlendFactor = .oneMinusSourceAlpha
+                    renderAttachment.destinationAlphaBlendFactor = .oneMinusSourceAlpha
+                }
+                renderPipelineState = try device.makeRenderPipelineState(descriptor: pipelineStateDescriptor)
+
+                try delegate.field.setupMetal(withDevice: device)
+            } catch let e {
+                fatalError("\(e)")
+            }
+        }
+    }
 
     private var device: MTLDevice
     private var commandQueue: MTLCommandQueue
-    private var renderPipelineState: MTLRenderPipelineState
-
-    public init(delegate: RendererDelegate) throws {
-        self.delegate = delegate
+    private var renderPipelineState: MTLRenderPipelineState? = nil
 
+    override public init() {
         guard let device = MTLCreateSystemDefaultDevice() else {
-            throw RendererError.MetalError("Unable to create Metal system device")
+            fatalError("Unable to create Metal system device")
         }
-        let view = delegate.metalView
 
         self.device = device
-        view.device = device
-
-        try delegate.field.setupMetal(withDevice: device)
-
-        let library = try device.makeDefaultLibrary(bundle: Bundle.main)
-        let vertexShader = library.makeFunction(name: "passthroughVertexShader")
-        let fragmentShader = library.makeFunction(name: "sampleToColorShader")
-
-        let pipelineStateDescriptor = MTLRenderPipelineDescriptor()
-        pipelineStateDescriptor.label = "Render Pipeline"
-        pipelineStateDescriptor.vertexFunction = vertexShader
-        pipelineStateDescriptor.fragmentFunction = fragmentShader
-        if let renderAttachment = pipelineStateDescriptor.colorAttachments[0] {
-            renderAttachment.pixelFormat = view.colorPixelFormat
-            // Pulled all this from SO. I don't know what all this does...
-            // https://stackoverflow.com/q/43727335/1174185
-            renderAttachment.isBlendingEnabled = true
-            renderAttachment.alphaBlendOperation = .add
-            renderAttachment.rgbBlendOperation = .add
-            renderAttachment.sourceRGBBlendFactor = .sourceAlpha
-            renderAttachment.sourceAlphaBlendFactor = .sourceAlpha
-            renderAttachment.destinationRGBBlendFactor = .oneMinusSourceAlpha
-            renderAttachment.destinationAlphaBlendFactor = .oneMinusSourceAlpha
-        }
-        renderPipelineState = try device.makeRenderPipelineState(descriptor: pipelineStateDescriptor)
-
         commandQueue = device.makeCommandQueue()
+
         super.init()
     }
 
+    public convenience init(delegate: RendererDelegate) throws {
+        self.init()
+        self.delegate = delegate
+    }
+
     /// MARK: - MTKViewDelegate
 
     public func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {
-        delegate.renderSize = Size(size: size)
+        delegate?.renderSize = Size(size: size)
     }
 
     public func draw(in view: MTKView) {
-        let field = delegate.field
+        guard let field = delegate?.field else {
+            return
+        }
 
         // Two triangles, plus texture coordinates.
         let points: [Vertex] = [
@@ -95,7 +111,7 @@ public class Renderer: NSObject, MTKViewDelegate {
         let buffer = commandQueue.makeCommandBuffer()
         buffer.label = "Render"
 
-        if let renderPass = view.currentRenderPassDescriptor {
+        if let renderPass = view.currentRenderPassDescriptor, let renderPipelineState = renderPipelineState {
             let encoder = buffer.makeRenderCommandEncoder(descriptor: renderPass)
             encoder.label = "Render Pass"
             encoder.setViewport(MTLViewport(originX: 0.0, originY: 0.0, width: Double(view.drawableSize.width), height: Double(view.drawableSize.height), znear: -1.0, zfar: 1.0))