M-LOK 5-7-9 and 11 slot rail segments

Requires M5 tapered head screws and M5 M-Lok nuts. Easy enough to find on Amazon or AliExpress.

Original model is printed rail down with no supports. I don't love this as the “nubs” (for lack of a better word) that are on the back and guide the rail segment into the M-Lok holes, have their layer lines in the weakest orientation. It shouldn't be an issue in a sharp impact as the force is supposed to be on the screws and T-nuts, but still worth considering.

I print mine on the rail edge (how it is photographed) which does require support on the screw holes and on the now horizontal part of the rail. This means the nubs are printed in the strongest orientation with the layers running across them. I also like the look without the overhang. 

I use a Prusa XL with Polymaker PLA Pro as the main material, with Polymaker Break Away Support as the interface, but any support will be fine if you don't have a multi material printer. 

If using this in an application other than airsoft, it is worth considering that handguards can get hotter than 140F (60C) which is a limit for PLA. If it is too hot to hold, that's hotter than the plastic can handle. I have not had this issue in my non-airsoft applications. PETG or Nylons should be used if you are in hot climates, but worth trying with PLA since it uses so little material.