Anyone know a custom woodworker who can make a case for a vintage receiver?

Maybe contact Lou Hinckley at Daedalus Audio , aside from building speakers he has done work for Modwright maybe he can accommodate your particular need

Find a local woodworker, support your community. 

Look on Etsy:

https://www.etsy.com/search?q=wood%20box%20for%20stereo%20component&ref=search_bar

Several wood enclosures available. Contact maker and ask for custom job. 
Or, contact your local cabinet maker. This is easy woodworking. Depends a bit whether you just want a face plate, or a whole enclosure and whether it requires ventilation slits/grille. I would make my own, but sorry, not offering to make yours. Already have too many projects.

Check out Timbernation. I just ordered a pair of walnut shelves; reasonable prices, infinite options. 

not a case, but I built a ventilated surround/stand for vintage tube equipment

New Jersey Hardwoods, Plainfield, NJ made and finished the pieces for me from my drawings and finish samples, I assembled them with parts from Amazon

full description, many photos here

https://www.audiogon.com/systems/9703

Can stack up to 100 lbs on top, the back is fully open for access, and the lower unit can slide out without moving the item on top

I’m about to sell my Fisher 500C Receiver, no case, I think I’ll include a surround/stand with it.