This locks the rails into position without clamping and also allows bed leveling. I've been using this since day one and it works great.
This requires 1.5" long bolts with locknuts and strong 0.5" springs. I used 6mm (1/4") plywood and cut and rastered this on a 35w laser. After cutting the pieces out and assembling them, I used a 8mm (5/16) drill bit to set the depth of the rod holes but it could probably be done using the correct raster settings on a laser. All of the features are different colors so you can control the print settings independent of each other.