- The plywood base isn't wide enough, so it's very hard to balance.
- The plywood base isn't stiff enough, so it flexes under my weight.
- The air connections need to be better, the duct tape keeps leaking.
- It's probably a good idea to strap the leafblower engine down to the plywood permanently - leafblowers are cheap nowadays.
To a zeroth-order approximation, there are two kinds of engineering styles, planning and prototyping. A planner tries to think through every possible detail or failure mode first, plans out everything on paper, and only then does he pick up his tools and start building. A prototyper begins with a general idea of his goal, grabs his roll of duct tape, and starts putting together the cheapest, cheesiest possible version that will work. With prototyping I discover principles and failure modes that I might never have found by thinking ahead. Besides, I get to take cool videos sooner than later.
When I was a young child, I was by necessity a planner because I didn't have any stuff to build with. So I'd think about things and imagine things and try to reason through as many implications and ramifications as I could. The balance between planning and prototyping is economical. The cost of prototyping is materials, labor, and the risk of problems that might have been avoided with planning. The cost of planning is time, and the risk of problems that can't be foreseen until you have a working model. Simulation is a half-way approach - a good simulator will alert you to problems you didn't foresee with pure analysis and design, but is cheaper than building a prototype.
But you can't shoot the video until you have the prototype. And the video is very cool.