Good stable design for the wheeled stool. The top is able to be locked onto the bottom, which is clever but for most of us - probably an inconvenience. I wouldn't want to get up and open the box to get a tool. How about if the sides were open and had the same slots and cubbyholes for tools?
Is it worthwhile? Absolutely. I use a wheeled stool all the time on the cars and motorcycles. Very handy to zip around to "the other side" and have all the tools at hand.
The round wheeled stools that are currently available in stores - I have one at home and one at work. The home version is from Tractor Supply I think - very stable even when rolling across floor, seat height adjustable, comfortable, lots of room on the square tray below. The one at work is a Craftsman, not as stable, does not roll as easily, bottom tray round and smaller, sides are not as deep, and it's adjustable but it is so low I had add a 4" spacer to bring the seat height to usable level. Oh and the seat is a lot smaller and a lot less padded.
So, some things to consider in your design. Use sturdy casters.
Al
