20x20mm template for fc? Help

Ok so my computer skills are really really bad. I’ve been trying to make a 20x20mm template so I can drill perfect holes to mount my flight controller to my frame. The problem is not drilling a perfect hole… it’s getting the perfect square and spacing. This is probably so simple but can anybody make a template to print out preferably with small dots so I can line up a 1mm bit for a pilot hole. I already ruined 1 frame. 3 screws line up but the fc is slightly cocked. Took it for the first flight And It doesn’t feel right. Actually all 3 screws snapped falling from 5 feet (to much tilt can’t see the ground at hover) My blx 117 with identical components Is 11grams heavier and flys better.

you’re ambitious!

Print the image of the template on a printable sticker A4 page after with razor blade cut the 2020square and discard the rest of the sticker. Now stick the 2020 sticker on the plate you want to give it that shape and with appropriate tools(dremel) cut and trim it. Tip when you cut it leave 1mm space so that you can trim it after and make it perfect square