Have to say, in all my time I've never seen such a thing in a shop. Might well be a 3D print file out there somewhere in the depths of the internet, or find someone who's a whizz with modelling software and ready your wallet.
Maybe kinda like this, ish...
People replying to Qs like this with DMs and preventing the dozens of potential readers who will find their way to this thread from getting useful info is crazy work.
I've had an AR AEG build in progress for a good while now, put a lot in to getting the exact parts needed, had helpful input from a few other peeps, but need just a couple of small markings altered on the lower receiver before it can continue (and hopefully get finished).
Will involve engraving...