Custom Backplate

I'm in the process of refacing one of my fireplaces. The Aztek Strip stones (http://ecosurfacesdist.com/wp-conte...ings/aztec-strips/erth-aztec-stone-strips.pdf) are varying depth by design so an insert will never fit flush to the stone. I'm thinking about attaching a backplate that conforms to the size of the fireplace opening and extends a few inches rather than putting the stone flush to the outside of the existing insert. The reason is that I eventually plan on getting a larger insert for that room now that I realize the fireplace can hold one if I have the metal heatilator plenum cut out entirely. If I have the the backplate as a buffer, putting in a new insert down the road should pose little problem. What is my best approach here to get a backplate made? Type of steel, etc I should be aware of? If figure I can match colors with stove bright in the event I make a change down the road.

Not a bad suggestion and would probably look much nicer than the backplate.

Followed your example...replaced the hearth pad tile and used that as a surround rather than the backplate.

It was a lot more work than I thought it would be. I can say with utmost sincerity I won't be picking natural stone with moisture sensitivity again. Having to use rapid set thin set for all those individual pieces sucked. If a dry run wasn't required maybe it would have been different, but Washington bucket and trowels ever 2-3 rows sucked after getting it all planned out and cut

Of course she needed a fire this evening