If you enjoy eating fresh peas from your garden, the only downside is shelling them--especially if you have a lot of peas. Save yourself some headache so you can get eating: Make yourself a homemade pea sheller.
Find Rollers for the Pea Sheller
Rollers are an integral part of the pea sheller, for it is through the rollers the peas must pass in order to be parted from their pods. Fortunately a thrift shop or a lawn sale can be a good source for these: look for a dot matrix printer with pretty hardy rolls.
Supply a Oomph for the Pea Sheller
Power the pea sheller with items that can be found at junk yards or even the dump. Look for an A/C motor, a large pulley and belt, and some bushings on which the shafts for the rollers will run. The pulley can come from an old washing machine and the belt from a truck. Add gears to run the roller and you've got the innards for your pea sheller. Just make sure you leave a gap of .05 inch at the end where the pulley's located, and .01 inch at the end where the gears are located.
Create the Case for the Pea Sheller
The pea sheller's case is made from plywood. The top should consist of a tray with 4-inch or taller sides with the rollers forming one side. The bottom of the case should be open on one side for easy access, with a chute beneath the tray down which the peas will fall after they've been shelled. In all, the pea sheller should be a little taller than counter height.