1) I used some spare 1"x2" wood to fill out the side table, although you could just push all the plywood together and leave a gap at the back... and
2) a second piece of 4' x 8' plywood was cut down to be the bottom shelf where the paint is going. I had toyed with using leftover wood for the bottom shelf, but in the end went back to get a piece of plywood. You could use something other than plywood which would be the actual size you need (1"x12" or pegboard or whatever) or even scrap boards you have already (whatever you can make fit), so this is why I didn't include it in the supplies list.
(I also have a vague memory of grabbing a spare 2x4 from the scrap pile to fill in something, but that might have been because of a cutting error)
Some extra dimensions to help with the side table:
- the legs were 24" tall
- the horizontal supports for the worktop were 41" long (b/c they attach to the main piece, so they need that extra length)
Also take a peek over to my other post if you want to see more photos of my version: the general build post, and the pseudo-finished post.
For finishing it, I used a light stain and then 4 coats of the polyurethane that spoke of being "as hard as a bowling alley" once it was dry. I really wanted this to stand up to time.
Nearly a year in now, I miss how smooth and awesome the worktop used to be. I've drilled a couple of holes in it by mistake (oops) and have gotten primer and paint on it too. I'm going to try to sand it all down and apply more poly, so that I can maintain the smooth(ish) flat surface. It's important to me as I use it for refinishing windows and building cabinets and other things where a balanced flat work surface is important.
ANYWAYS, for those not interested, I hope you didn't read this whole thing ;) For those who were looking for this, apologies for taking so long: life got in the way!