I wonder how realistic it is to get the simplest ARM design and make "your own" chip? I mean there should be blueprints somewhere, if you could ask someone to m

I wonder how realistic it is to get the simplest ARM design and make "your own" chip? I mean there should be blueprints somewhere, if you could ask someone to make a small batch of these chips? It would be too small to be worth it for someone to inject a backdoor into it. Or you could make that into an FPGA... Am I talking nonsense?