Replying to DIY Mounting Jig

Aight so how could I do this? I have Pivots and will most likely use only pivots for the next 10 years probably... so naturally it’s gonna be 10x cheaper to make a jig and mount myself than have a shop mount 2 pairs of skis each year (shops around here mount expensive). I saw a YouTube video and the guy mounted his bindings into a quarter inch thick peice of plywood. And I believe he would then use the plywood with the holes already mounted and use that as a jig once he actually mounted? This seems sketch tho because it seems like that peice of ply would be very tough to center perfectly once you put it on the ski. Plus it would also be difficult to mount centered, a few cm back, etc.

Someone help me out here, if you can think of any ways I could build one for cheap that will do the job just fine, or if you’ve made one, drop it below. Thanks.