The basic information is as follows:

• Base is basically a holder to keep everything securely together so it doesn't fall apart as you work with it. 
• The top is fine grain graphite drilled for the pins and a nice slip fit to the base. 
• Pins are solid brass pins that are held in the Vin Pin.
• To change designs, simply unscrew the base hold down screw. Invert the tool and allow the top to separate from the base. Remove as many pins as you want to alter the design and reassemble.