You can make one, but I would be surprised if someone would do it for a lot cheaper than what they sell for. You can typically pick them up used for a fair price.
I made one years ago, because I didn't want to dish out the cash for a MP one. I think it came out good, but I don't have any comparison numbers. I just did it for something to make...
Here is something to give you an idea... It changed shapes a few times, but the final design was when it was painted and assembled. It also has added material so that it can be bored out to accept an 85mm TB.
It can be done, you just need to find someone willing to make one for the right price. (not me)
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