DIY High-Speed Book Scanner from Trash and Cheap Cameras

Step 67: Handle/Electronics: Mechanicals 2.

Add another nut on the outside of the last nut you put on. Drill a 1/4" hole through a scrap of wood or HDPE. Put another nut on the other side of the polyethylene. You can put washers on both sides of it for added stability. Conclude this hardware stack with a wingnut. Using the wingnut and a crescent wrench, you can now adjust the tension on the plastic block (which adjusts how freely the handle rotates). The purpose of the wingnut is to lock the inner nut from rotating on the shaft.

Thread in the tailcap with the new switch. Admire how cool this thing looks.