I used the following two kits to get parts I needed to build my LEGO abacus:
- LEGO set No. 8032 Generic Construction Set (bricks)
- LEGO set No. 8412 Nighthawk Helicopter (axles and connectors)
If you are a LEGOmaniac, you can gather the parts from whatever kits you may have available.
Instructions & Complete Plans
Click on each image for the enlarged version.
The LDRAW file, Abacus.ldr, is available for download. I designed the model using Bricksmith, the Mac version of LDRAW.