Not a critique but general advice - make sure that the height of the cart + the height of a robot fits through a standard doorway as well as every doorway in and around your shop. Otherwise you’ll be in for a nasty surprised the first time you try to take the robot anywhere.
I would definitely close off the front and the back of the base so you can put things there without them falling off. Ours always has a number of needed tools, spare battery, zip ties, duct tape, etc and they would likely bounce around and fall off when moving the cart. We also added a few dividers so we have a place for batteries and water bottles. Initially we kept all batteries in the battery section, then found it made sense to put only charged ones there, and if we had a dead one that couldn’t go straight to the pit, it would go in the bigger open space so we didn’t confuse them. Yeah, charged / dead battery tags would be better, but we didn’t have any
looks great to me. only suggestion is add a toolbox underneath. but that would negate your ability to reach under the robot. we have found having the toolbox on the robot transport has been great when you need to do maintenance in queue. for example quick turnaround matches, playoffs, finishing work that started in the pit, noticing something that was missed, etc.
also we always carry a spare battery with us in case something goes wrong, so we have a spot on our cart for those as well.
My son’s team built a flat deck cart like that but larger. They were going to build a support structure to raise the robot up to make it more convenient to work on but never got around to it. They ended up using one of the many totes they had accumulated. The tote was typically used to bring parts or tools to the competitions and would otherwise be in the way.
118 uses a large flat deck cart with Velcro covering most of the top surface. They make a support structure to fit each years robot (or not) and secure it to the top of the cart with the other side of the Velcro. Some years, the support structure is just a few pieces of 2 X 4.