How to mirror fiberglass for opposite side?

You should have made two of all your parts as you made the irst one and made detailed plans as you made it or made them at the same time.  Now youve got to eyeball it you can get it close but unlikely perfect.

try taking your pics in photoshop, and printing them up in sections to actual size (use a ruler in your picture just to make sure that it's an "actual" actual size..... print up all the sections and assemble them on a piece of cardboard to where you have a life size reverse picture of the actual panel.  this can help get your reverse curves and angles (not to mention vertical and horizontal dimensions) exactly the same for both sides - not to mention, just having the actual size picture as reference, you can use it for comparison and see if / when you go wrong somewhere.

Hey Superchuckles,

have you done this before- mirrored a panel using latex, and where do you get it?  That sounds like a good idea if it'll work.  I understand when you take it off to flip it inside-out it's flimsy so it needs reenforcement.  What's that celotex stuff, and where do you get it?

the reason i suggested celotex is because i personally just happened to have it, and i've used it before for making the backing of a "rough in" mold before.   you can get it at building supply places like home depot possibly - it's hard sheet insulation - something that would work the same is once it dries, expanding foam.  it's about the same consistancy, and is super easy to model with a razor or exact-o-knife.  in fact, almost any knife goes thru it like butter, making it ideal for shaping as you desire.  the latex you can find at hobby stores, not sure what's in your area so it's hard for me to say

https://www.artmolds.com/gateway/studio/catalog/kits/latex_mold.htm

you can get latex from these people.  doing this method will get you "in the ballpark" to having your exact mirrored piece.... depending on how much time/effort you put into making the backing.... and how elaborate the origional piece is.  just remember, if there are any recesses, etc in the door panel (like handholds, or handles) you'll have to fill them in with modeling clay before pouring the latex, so the eventual cast will be able to have the finished  product pulled from it (also so you can reverse the latex mold).  then you can cut thru the area where the clay was when finished.  to answer your question, yes - i've done something similar to this before, but not as big as an entire door panel.  getting the latex on smoothly is something you want to do, but not too terribly important if when you reverse it, and make your inverted piece, if you put all the finishing touches on the reversed piece (basically, the first reversed door panel you make out of the latex mold).  make that first piece quickly, and thick, so that you can sand/cut/groove/shape it to the way you want the finished product to look, then you can make yourself a more permanent casting from plaster and use it to create a near perfect mold to make your panel(s) from.  parts release easily from plaster, and i've made pieces that are impossible to tell from the origional with them -- the detail is nearly 100% perfectly transfered with a plaster cast, so any imperfection in your door panel will be copied into it.   also, remember the latex mold will not be perfect on the "reversed" side - especially on any edges that are particularly sharp.  that's why i suggest making your first door panel from it just as a piece to use to make your plaster (permanent) mold.  you could even make that first panel simply out of resin (to make it a bit easier to shape) since you'll only be using it to make your permanent plaster mold from.

Cool!  Yeah, I'm experimenting, trying to rebuild my kicks.  It's not fun to try to just eyeball everything to get it right.  I picked up some mold rubber at the hobby store, so I'll try it out.  Thanks.