This shop-made miter clamp has many of the same advantages as the expensive metal ones. It’s strong, easy to use,holds project parts both square and flat and allows you to adjust one part at a time.The slot in the bottom lets you examine the back of your miter to make sure it’s properly aligned. It also keeps glue from smearing on the miter’s back.
It’s simple to make this clamp out of some scrap plywood.Make the center 4-in.-square block from two layers of 3/4-in.plywood glued together. Double- check that this block is perfectly square and drill a 2-in. hole in the middle.Make the bottom board 7-in. square, cut the slot with a jigsaw and glue it to the 4-in. block.