A slight modification to Gossamer's thing that adds sections with a narrow diameter at the bottom of the bolt head holes. This makes it less easy to install (you have to completely remove the bolts) but I think this will make it less likely to slip off the bolt heads if tension is high and helps spread the force from the bolt heads across a larger surface area preventing damage to the plywood or acrylic. In my case the bolts had already been over-tightened which lead to deformation of the plywood and cracks in the acrylic.Note1: It might help to drill some 6mm holes in the left side panel of the printer so you can access the bolts holding the left end piece to the Y-Carriage without having to remove the Y-Rods and Y-Carriage. I made mine at the Y-Home position for easy repeatable location of the bolt heads (see picture).Note2: A 4.4mm hole allows you to use the little clear plastic collars from the end of the ABP rollers as hole inserts with built in washers to protect the plywood from being damaged if you over-tighten the tension screw. If you do not have any of these to spare you should at least use a washer or two!