proper tool for trimming aluminum sheet from sides?

OK Ive got the sides up with a benroy type of shape in mind.

Instead of actual .032 alum sheet, Ive acquired some 1/8 inch composite aluminum/plastic panels. They are basically .050 alum on both sides, with plastic resin sandwiched in between. Total thickness is 1/8 inch, and these are usually used to cover the outside of newer Chevy dealerships. Gotta love craigslist!
Anyway, I had planned on using my router with an as yet unknown type of bit to reproduce the radius curves already in the 1/2 birch plywood sides. The bit would need some sort of guide, so I wouldnt have any danger of cutting into my plywood sides, as I trim the alum panels. Anyone know of such a bit or a different tool? Ive also considered using my Zip tool, but again, need the proper bit/attachment. I would just lay the alum panels flat and cut the same curves with my jigsaw, but I really hate how wobbly and prone to miscuts that jigsaw is. Id rather use something that will trace the existing curve, so I dont have mistakes.
Wondering how others have gone about this.....my first build I glued then cut the panels with the sides all in one shot, but for various reasons didnt want to do that this time.
Instead of actual .032 alum sheet, Ive acquired some 1/8 inch composite aluminum/plastic panels. They are basically .050 alum on both sides, with plastic resin sandwiched in between. Total thickness is 1/8 inch, and these are usually used to cover the outside of newer Chevy dealerships. Gotta love craigslist!
Anyway, I had planned on using my router with an as yet unknown type of bit to reproduce the radius curves already in the 1/2 birch plywood sides. The bit would need some sort of guide, so I wouldnt have any danger of cutting into my plywood sides, as I trim the alum panels. Anyone know of such a bit or a different tool? Ive also considered using my Zip tool, but again, need the proper bit/attachment. I would just lay the alum panels flat and cut the same curves with my jigsaw, but I really hate how wobbly and prone to miscuts that jigsaw is. Id rather use something that will trace the existing curve, so I dont have mistakes.
Wondering how others have gone about this.....my first build I glued then cut the panels with the sides all in one shot, but for various reasons didnt want to do that this time.