It’s just a fact of life in this hobby. You’re going to make a mess.
Realistically, there’s probably more ways to make a mess while building model kits than there is in any other home hobby.
You can make a mess of a model:
This is the cab of the Bigfoot kit that I just bought as ‘partially started’. If I had to make a recommendation to you guys, it would be not to buy partially started kits unless its something old and hard to find, like this kit. The previous owner started brush painting everything, and its thick, ancient Testers enamel...this shit is going to fight me the whole way taking it off. I’ve heard good things about Easy Off oven cleaner for taking off old paint, but I’m loathe to try something new for the first time on something like this...I might just take a sanding sponge to it and see if I can’t even it out and paint over it without losing much detail.
You can mess up your spares:
The box in the first picture there is available at Harbor Freight, and I recommend it. The second box is from an AMT kit, which is fine, although the kit itself wasn’t great. Some day I’ll go through all this stuff and sort it by car type and part type, but today is not that day.
And of course, you can mess up your work space:
That right there is too many projects at once, plus garbage. There are parts to my ‘66 Fairlane 427 I’m working on, there are slot car parts (both 1/32 and 1/24), there are multiple helping hands...its just a shit show. It all cleans up fairly easily, but it can be a bit difficult to navigate if you let it get too bad. I’d recommend leaving sprues in the box whenever you’re not actively working with them...I should also take my own advice on that.
So those are just a few of the ways you can make a mess with model kits. Notice that I didn’t even talk about spilling paint on the floor, or the cat vomit I stepped in while taking those pictures (true story). I’m sure somewhere out there is a model builder with a perfectly clean work space, but that person is deranged. Give me a mess that I know...the second I start organizing is when I start losing parts.