This is a simple landing gear for a quadcopter or tricopter that uses square/rectangular booms/arms.
Just use a 2 zip-ties to fasten this to an arm.
OpenScad version also uploaded so you can change the length of the landing gear.
Default size is 110x20mm.
The distance between the holes can be changed as well (Default 12.7mm).
I found this idea in a flitetest tricopter video.
Two of my landing gears broke on a crash. So added the T format to the design.
Print 1 per arm/boom, and attach it with 2 zip-ties.