Headset holder for wall rail

Headset holder for wall rails. The rail it's designed for is from Biltema. The slots are about 18mm high, 2.75mm wide and centerlines 11mm apart.

It's a little difficult to print. I suggest printing on the side with 0.1mm layer height, and regular support as shown in the last picture. Printing on the side will give the best strength for the inserts.

Freecad file supplied if modifications are needed. :-)