Long ago, in a galaxy far, far away ....
I had something called a Paperweight Kit. Basically a few different size and shape molds. Just pour the resin into it, let it solidify, and remove it.
Whatever you want to encase needs to be suspended in the middle, so the thicker the resin, the easier to do that. Sometimes you need fill a small amount in the bottom of the mold, let it cure for a short time, then add the object and rest of the resin. If you aren't careful, you'll have the object off center or even close to protruding.
The molds are usually upside down when filling, so make sure the object is also.
Very simple process with a few gotchas.
It might be cool to look around for, or 3D Print, a mold that has a recessed image of a 1911. You could also just include a small charm or toy 1911 in the resin with some separation between it and the phone for a 3D look.
