We had a drawer in a cabinet that was pivoting side to side instead of straight in and out. When I took it out, I saw that it was meant to run along a center rail. The plastic guide was broken.

10 minutes of OpenSCAD later (and 17 minutes of printing) and I had my first draft. It worked great, but I wasn't able to use the screw holes I modeled in--I just air nailed right through the PLA, which worked better than expected. Also, I originally had 3mm wall thickness. It was sturdy, but a little overkill. 

I upgraded the model, which is what is uploaded here:

• customizable parameters
• thinner walls
• wider bearing plate
• screw holes in the back to attach to the back of a drawer

I have attached photos of the first draft print, but the uploaded files are better.

If customizing to fit your drawer rail, change the width parameter to have whatever wiggle room you (and your printer) need.