Excellent beginning. Looks nice too. A couple of thoughts.

I wonder about a longer tray or a two tray setup, one for the drum and the other for chemicals. I often do a large run of multiple drums so it is nice to have a tempering bath with the chemicals ready to go.

It the temperature adjustable? Phototherm made submersible heating elements with a thermostat that work very well and would be goof for your setup, perhaps with a very small aquarium pump to circulate the water.

Do the rollers also work with Expert drums? I use a smattering of 1500, 2500, and expert drums.

Obviously, the motor is going to be the most difficult part. I don't mind manually emptying the drum and pouring in new chemicals. But the motor is the real labor and drudgery saver. It would be best I think if the motor moved a mechanism that could rotate any type of drum from BTZS tubes to Jobo Expert drums without need a special attachment point like a cog lid or a magnet. Kind of like a rotisserie basket or some mechanism that does not require the use of one brand/style of drum. I don't know how to do that but I think that a clever craftsman could develop a new, poor man's Jobo with off the shelf parts and good craftmanship that many people would buy.