ERLT transponder box - enclosure

I have many EasyRaceLapTimer transponders (Dual-LED version, see here https://oshpark.com/shared_projects/iAKUTDP4 or https://oshpark.com/shared_projects/4ZlOlKub - just use with ~4ohm resistor for LED's if you want max brightness) but during race they are somewhat hard to mount quickly, even with heatshrink and velcro.
This small and simple box adds "flat bottom", mounting holes for zipties (if needed) and allows to simply ziptie entire box somewhere on copter without additional rubber pads.