Make Noise make really really good stuff, I think im going to have a separate skiff case filled purely with make noise utilities in the future (If main case does not fit).
You will definitely want a Maths, theres no reason not to have one in a modular system.
Making a case isn't too hard, all you have to do is make the side panels, a base plate panel (if needed), a back plate panel (if needed), Rails and a power supply.
For custom cases just buy everything from synthracks.com, they sell sets of rails secured in brackets so its really easy to line stuff up and drill holes etc.
https://synthracks.com/shop/eurorack-frame
Then for PSU just use either:
(1) TipTop Audio uZeus module with break out cable and a Power Brick. (You can use however many uZeus you need, can have one in each row of your case etc.)
(2) TipTop Audio Dual Access module and some TipTop Audio Studio Bus Boards and a Power Brick.
The second option delivers more power and allows for 6x Studio Bus boards to be connected to 1x TipTop Audio Dual Access module, the Studio Bus boards have 14 connectors compared to the breakout cables 10 connectors just another thing to consider.
You don't need to be super techy, you just need a clear idea of what you want to achieve in the end, theres no 2 ways about it you will be spending alot of money lol.