Oops clamp for ¼-20 hardware. Inspired by the OneFinity product.

Stick a hex bolt through the middle sliding section into your spoilboard threaded inserts. I use a short carriage bolt on the back side to keep the clamp parallel to my workpiece.

If you often work with stock of the same depth, you may want to fasten the Hex bolt loosely in place with a nylock nut.

You may need to ream out the printed parts gently with a ¼" drill bit, but they're meant to be a very snug press fit. I assemble these by pressing them together with my bench vise. The sliding middle piece should move fairly freely along the aluminum rods.