I have a KR-3200 I was given for free. It did not have its cover when I was given it, so I decided to make one myself, as I do woodworking as a hobby. Used 3/4 inch red oak and stained it with Minwax "walnut" stain. Not sure what color the original covers were, but I do like the dark wood look. I suspect the original case was 1/2 or 3/8 inch plywood, so this case may look a bit bulky compared to original. I "book matched" the two side pieces, cut from one board and then placed in a mirror image of each with the pattern of the end grain radiating outward. I like the effect.
I ended up using window screening for the air vent area. It just made making the case easier.
After cleaning up the receiver I was so impressed by the sound that I purchased a KR-4200 that I found locally. It's all original, but doesn't look any different than the others posted here, so did not take a picture yet.
I've got a nice KR-5200 that I bought from the original owner... it just needed some cleaning, including the relay. The cover is perfect and it even came with the original box. I'm setting it up as a house system for my wife and daughter. Here it is after cleaning while I used it for over a week to make sure it was running proper.
Nice little Kenwood score, all in great working order. Really hard to find any info on the speakers (KE-3, Two-Way). Glad to get the original boxes, and amp manual.