I have a gentleman here in Columbia that has made some for me. We have gone through a period of learning but he has the 400/500/800 size down pretty well right now.
I don't know if he wants to deal with shipping and all but it can’t hurt to ask. If you’re interested, pm me and I’ll give you his number and you can work it out with him. Also that is with no screen (but the channel is there for you) and no feet. You would have to go over all of that. The holes are drilled for mounting screws and there are cooling cut outs on the bottom.
I don’t want to break any AK rules so I won’t say anything about price, you can work it out with him. But they are less than anyone else I know of.
Here is the first one he made for me and a recent one in the condition I pick them up from him.
I get nothing from this, just helping out fellow AKr’s.