I wanted to make some rail to allow me to used containers as drawers, with the minimal print material. Here is the result. Print 2 of the brackets for each rail (4 per drawer). Insert 3/8 square dowel (I added a little glue to mine), and use a wood screw to set in place. There are end pieces (support 1 rail) and "middle pieces" to support 2 rails. (See the pictures). I have revisions that print a covered size, so you don't see the wood rod...if anyone is interested I will add it. I will add the OpenSCAD files if there is any interest.
I suggest printing with 20% infill. That seems to provide adequate strength.