As I use my cheap vise (I think it was Leroy Merlin bought for about 20$ or so), more for holding stuff than heavy duty work, I made a knob that makes it easier to open and close the jaws. I used a M8x80 screws I had on hand, to make a small “lever” in case I have to clamp something with more force, but use any thing that fits, and scale the screw cover. STEP files included, so feel free to iterate to your needs.