A seal press having a single U-shaped stamping of heavy steel plate with a handle removably assembled in pivotal relation astraddle the upper arm. A spring opened die unit is received in the throat of the stamping to rest on the lower arm to support the lower die in place with the handle and upper die urged to open position. A slidable catch locks the handle in closed position and two plastic side members fastened to the stamping, protect and hold in operative relationship the working parts.