My wife is from "up north." She still has trouble keeping it straight between "shucking corn" and "shelling peas." Years ago dad acquired a small pea sheller. The rollers were probably an inch or so in diameter and about 4 or 5 inches wide. Worked on the same principle as the rollers in an old wringer washing machine. A drill provided the power. Using a variable speed drill you could adjust the roller speed so that it would squeeze out the peas rather than mashing them. The peas needed to be fully ripe and it helped if the pods were wet, or at least damp.