This is a rope tensioning device that I designed for 3mm and 4mm utility cord (paracord / 550 cord is usually 4mm diameter). The goal was to produce a paracord buckle that was versatile lightweight and strong to use while hiking and camping. This weighed in at about 0.2 oz and is strong enough to use for tarps and tents. The device was modeled after a climbing ascender but it should go without saying that you should not use this device for climbing or load lifting. The tensioner utilizes a toothy looking elliptical cam to lock the cord down and small rubber band to keep the teeth engaged. You will also need a 3mm x 10mm bolt and nut to hold the parts together. A nylock style nut would be preferable but a regular hex nut will work fine. The 5mm hole in the base plate will accommodate a wide variety of mounting and rigging hardware. You can use it with an S-hook or mini carabiner, tie it up or screw it down. If you ever use paracord you are bound to have a use for this thing.
0.3 mm layers work fine
while prototyping, I printed in pla with no support and I didn't have any issues with the overhangs.
I found great rubber band to use. Try the bands from a rubber band bracelet loom. They are available at most department or craft stores (in every color imaginable) and cost next to nothing.