I found all the materials for this project laying around at home and there were no plans nor designing. I just took the materials and thought how I can assemble them altogether.
You can use other materials and basically it's a good practice to design and make plans beforehand.
1 wooden Labyrinth - 280/230/60 mm
1 wooden board - 400/350/20 mm
4 pieces of wood – 30/30/10 mm
2 pieces of wood - 150/155/10 mm each
2 pieces of wood, L shaped – 120/27/4 mm each side
4 pieces of wood, L shaped – 34/32/8 mm & 18/32/8 mm each
600 mm long strong silk string
8 pieces of rubber – 30/30/1 mm each
4 L brackets, stainless steel – 32/32/1.5 mm each
8 bolts (40/5 mm) with nuts and washers
A bunch of small wood screws and nails
a piece of paper, A4 for example
2 Hitec HS-311 Standard servos
AVR ATmega32 and a programmer – I use the AVR-LIP (EC-AVR) by DeccanRobots
2 straight switch knobs
Some wires and pins
saw, screw-driver, hammer, sharp knife, scissors, clamp etc.