I've actually done a lot of indoor spraying during winters and after enough trial and error its kinda easy you just have to consider how the air will be blown as it blows off the different surfaces but something like this I would tape it off on top, down one side, along the bottom, and up the wall to make a "pocket" with one opening to spray from then grab your shop vac and either have someone hold it or tape it in place. It's kind of a lot of work but I prefer spray paints over roll ons. I've torn down modded and spray painted a computer tower all on my computer desk with no mess and all hardware working fine in the end lol