If you're talking about the ash, what I did with mine is bolted the legs of the charcoal basket through a cheap 18" pizza pan. The pan sits on the bottom of the UDS about 3" below the bottom of the basket. I just lift the whole thing out to dump the ash & stuff.
I didn't think about it when I built mine. I ended up with a huge basket and couldn't find an off-the-shelf pizza pan to fit. Ended up cutting a water heater pan to size an bolting to the basket. I still have foil below that though, to catch everything that slips through. But it's bc I don't have a shop vac