diff --git a/MetaballsKit/Metaballs.swift b/MetaballsKit/Metaballs.swift
index 8355307..d9ae4a1 100644
--- a/MetaballsKit/Metaballs.swift
+++ b/MetaballsKit/Metaballs.swift
@@ -10,7 +10,7 @@ import Foundation
 import MetalKit
 
 public enum MetaballsError: Error {
-    case couldntAddBall
+    case metalError
 }
 
 public struct Ball {
@@ -75,25 +75,27 @@ public class Field {
         }
     }
 
-    public func add(ball: Ball) throws {
-        guard bounds.contains(ball.bounds) else {
-            throw MetaballsError.couldntAddBall
-        }
+    public func add(ball: Ball) {
+        guard bounds.contains(ball.bounds) else { return }
         balls.append(ball)
     }
 
     // MARK: - Metal Configuration
 
+    private var ballBuffer: MTLBuffer?
+    private(set) var sampleTexture: MTLTexture?
+
     /// Create a Metal buffer containing the current set of metaballs.
     /// @param device The Metal device to use to create the buffer.
     /// @return A new buffer containing metaball data.
-    public func makeBallBuffer(withDevice device: MTLDevice) -> MTLBuffer? {
-        let sizeOfBall = MemoryLayout<Ball>.size
-        let length = balls.count * sizeOfBall
-        var ballBuffer: MTLBuffer? = nil
-        balls.withUnsafeMutableBytes { (buffer: UnsafeMutableRawBufferPointer) in
-            if let bytes = buffer.baseAddress {
-                ballBuffer = device.makeBuffer(bytesNoCopy: bytes, length: length, options: [], deallocator: nil)
+    private func makeBallBufferIfNeeded(withDevice device: MTLDevice) -> MTLBuffer? {
+        if ballBuffer == nil {
+            let sizeOfBall = MemoryLayout<Ball>.size
+            let length = balls.count * sizeOfBall
+            balls.withUnsafeMutableBytes { (buffer: UnsafeMutableRawBufferPointer) in
+                if let bytes = buffer.baseAddress {
+                    ballBuffer = device.makeBuffer(bytesNoCopy: bytes, length: length, options: [], deallocator: nil)
+                }
             }
         }
         return ballBuffer
@@ -102,14 +104,16 @@ public class Field {
     /// Create a Metal texture to hold sample values created by the sampling compute shader.
     /// @param device The Metal device to use to create the texture.
     /// @return A new texture.
-    public func makeSampleTexture(withDevice device: MTLDevice) -> MTLTexture? {
-        let desc = MTLTextureDescriptor()
-        desc.pixelFormat = .r16Float
-        desc.width = Int(size.width)
-        desc.height = Int(size.height)
-        desc.usage = .shaderWrite
-        let texture = device.makeTexture(descriptor: desc)
-        return texture
+    private func makeSampleTextureIfNeeded(withDevice device: MTLDevice) -> MTLTexture? {
+        if sampleTexture == nil {
+            let desc = MTLTextureDescriptor()
+            desc.pixelFormat = .r16Float
+            desc.width = Int(size.width)
+            desc.height = Int(size.height)
+            desc.usage = .shaderWrite
+            sampleTexture = device.makeTexture(descriptor: desc)
+        }
+        return sampleTexture
     }
 
     public func computePipelineStateForSamplingKernel(withDevice device: MTLDevice) throws -> MTLComputePipelineState? {
@@ -123,11 +127,15 @@ public class Field {
         }
     }
 
-    public func computeEncoderForSamplingKernel(withCommandBuffer buffer: MTLCommandBuffer, state: MTLComputePipelineState, balls: MTLBuffer, samples: MTLTexture) -> MTLComputeCommandEncoder {
+    public func computeEncoderForSamplingKernel(withDevice device: MTLDevice, commandBuffer buffer: MTLCommandBuffer, state: MTLComputePipelineState) throws -> MTLComputeCommandEncoder {
+        guard let ballBuffer = makeBallBufferIfNeeded(withDevice: device),
+              let sampleTexture = makeSampleTextureIfNeeded(withDevice: device) else {
+            throw MetaballsError.metalError
+        }
         let encoder = buffer.makeComputeCommandEncoder()
         encoder.setComputePipelineState(state)
-        encoder.setBuffer(balls, offset: 0, at: 0)
-        encoder.setTexture(samples, at: 0)
+        encoder.setBuffer(ballBuffer, offset: 0, at: 0)
+        encoder.setTexture(sampleTexture, at: 0)
         // TODO: Decide on actual values for these
         let threadgroupsPerGrid = MTLSize()
         let threadsPerThreadgroup = MTLSize()