Egg puzzle - prototype

This is a test of concept & implementation for a layered, ball-bearing  maze-type puzzle.  I think a wood version would be great, but I had to test the idea first. 

Each layer of the egg puzzle has some holes, which can go straight down, curve and go down or only go part way through to the other side.  Each layer also spins around a center pole.  The goal is to get a ball through all the layers of the egg.  In the default position (slices aligned to form nice egg shape),the ball can only go through one layer at a time. The player inserts a ball into the top layer, twists that layer to the right or the left, until the ball falls through to another layer.  (Metal balls work best because you can feel and hear them fall through the layer.)  Twist the each layer  to get the ball down to the next layer, until the ball rolls out of the bottom layer.  Some holes are 'traps' and do not let the ball pass through, if this happens, invert the puzzle and go back up a layer to try again.

I used
blue styrofoam insulation (2 inch foam insulation board)
a sharpened wood pencil
a thin-bladded, serrated knife (pumpkin carving knives work well)
a hack saw (optional)
drill or cork hole cutter
acrylic craft paint
small metal ball bearing (a small 'steelie' marble)

Step 1: Overview

The egg shape is sliced into layers.  A hole with a specific radius from the center of the layer can line up with a hole in the next layer, as long as both holes are at the same position.  In the diagram, hole A in the top layer is at the same radius as hole A in the second layer.  From the start position, the top layer is rotated clockwise until both holes align and the ball falls into the second layer.  The hole in layer 2 is cut at a slant and ends at a different radius from the top of the hole.  If layer 2 is twisted clockwise, the ball will fall into hole A in layer 3, which is at the same radius as the bottom of hole A in layer 2.  Turn layer 3 clockwise and the ball will fall into hole A on layer 4.  Turn layer 4 counter-clockwise to reach hole A in the bottom layer.  The holes in the bottom layer slant so the ball will roll out of the side of the egg, giving you a chance to catch the ball before it hits the floor.
 
The hole at position B has a variable path.  Turn the top-counter clockwise until both B holes align and the ball falls to layer 2.  Turn layer 2 counter-wise and the B holes will align, dropping the ball to layer 3.  Layer 4 has a trap.  If you turn layer 3 counter-clockwise, hole B will align with a grey hole at radius B.  This hole only goes halfway through the layer and the ball is trapped.  If layer 3 is turned counter-clockwise, the ball will fall into the while B hole on layer 4.  Rotate layer 4 clockwise and the ball will roll through hole B in the bottom layer, and out the side of the egg.