This is a functional Van de Graaff Generator made with a lasercutter.
This machine can generate sparks 20 cm long.

Part to cut in acrylic 5mm:

• lato1 (2 PZ);
• lato2nospazzole (2 PZ);
• lato2spazzole (2 PZ);
• spazzola_sopra (1 PZ);
• spazzolavader (1 PZ);
• supsfera (2 PZ);
• distanziali (8 PZ).

Part to cut in plywood 6mm:

• base4vader (1 PZ);
• base3vader (1 PZ);
• base2vader (2 PZ);
• base1vader (1 PZ).

Part to cut in plywood 4mm:

• base3vader (1 PZ);
• coperchio_sopra (1 PZ).

Lathe pieces:

• 1 PZ (barrel shape) PVC pulley 100x40mm (diameter) (top pulley);
• 1 PZ (barrel shape) Nylon pulley 100x40mm (diameter) (bottom pulley);
  Can be enough 1.5 mm difference between center and sides.

other pieces:

• 4 PZ FL08 bearing;
• 1 PZ natural rubber belt 900X90mm, cut with V shape and glue with contact adhesive;
• 1 PZ fan motor like this: https://goo.gl/sp8T7X;
• 2 PZ 40 Pins Male Single Row Header Strip;
• 2 PZ IKEA 36cm BLANDA blank (http://www.ikea.com/it/it/catalog/products/00057256/);
• 4 PZ M8 rubber feet;
• 1 PZ 175mm M8 threaded bar;
• 1 PZ 150mm M8 threaded bar.
• 36 PZ M3x16mm (acrylic joints);
• 8 PZ M5x16mm (bearing);
• 4 PZ M5x30mm (brush support);
• 4 PZ M3x25mm (sphere support);
• 4 PZ M6x40mm (base union);
• 2 PZ M4x20mm (motor support);
• 1 PZ M6x25mm (ground point);
• 1 PZ 50mm rubber pipe (internal hole 5mm);
• 2 PZ hose clamps;
  And some nuts, washer and wire.

I added a fan to cool the motor when it work for long time.