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

HiFi Caseworks does exactly that, I've talked to them in the past about a case for my Tubes4hifi amplifier; their quote was very fair in my mind. I have a friend who had one made for a vintage Onkyo that looks beautiful

https://www.hificaseworks.com/

perhaps consider constructing by your own kind self . perhaps also via Ancient Japanese Woodworking Technology which utilizes no glue nails etc. only hand tools ..perhaps also consider a fanciful / artistic / imaginative design as a proud work of art . many such highly skilled can be found on YouTube for examples of what can be achieved .  

Do not get a case like that shipped. It is the easiest thing to crush. This is basic cabinetmaking. A first month apprentice would be able to master this. Go to a local cabinetmaker. Drive there with the unit you want covered. They will measure it and make one on the spot. Tell them you will finish it at home(ie stain/ varnish/laquer),

Do not go to a franchise wookdworking firm. Find a local independent. It’ll save you shipping plus the hassle when it gets destroyed as it inevitably would. Saves the franchise added cost. More than likely a better quality end result. Ask for mitered corners and take along a phone or laptop with photos of cases you like the look of.

This fellow does excellent work.

https://www.etsy.com/shop/outboxed

Tim