These little bits of plastic will let you mount sheet metal endstop flags and then adjust them with as needed.
You'll need some M2 bolts (20mm and 10mm), nuts and washers and a bit of sheet metal. Tools required are a 2mm drill bit for cleaning out the holes and drivers for whatever bolts you bought.
I recommend printing the parts out of ABS as I suspect that PLA will be too brittle. Clean the parts up with a knife and the drill bit. Press the M2 nut into the part as seen in the photos making sure to center it. Thread in the M2x20 bolt. Cut a strip of sheet metal out for the flag and drill a 2mm hole in the end for bolting to the mount. Use an M2x10 bolt to mount the flag. The x/y mounts just press in to place. The z mount bolts up with 2 more M2x10 bolts and nuts with washers under them.
Before running the homing procedure on your bot make sure that the flags work and the endstop LEDs light up. Once you get the flags roughly the right length use the M2x20 bolts to adjust things til it's just right.