If by metal side plate you mean strike plate they are very easy to make if your not concerned w/having original parts. I simply got a 12" piece of brass stipping from the hardware, cut it to size, eyeballed and bent by hand, rounded the back edge, sprayed w/Plasti-Dip, and then covered w/velcro. I used a metal set screw (also from hardware) to make it operational. If interested I have approx. measurements and "instructions" on how to fabricate I can send anyone who wants it. Good luck.
PS...if your interesed in how mine looks check out my "Newbie Bear Takedown A Mag Refinish" thread on here.