Spackle is a white paste substance used to patch...er... holes in a booth. It is not intended as a stopgap measure for booths' wall section gaps.
To apply spackle, give the bucket of spackle and a spackle knife to a Spackle Fairy and send them to the booth. Overnight, what may have been a pretty good paint job will now have large crumbly white lumps in the design.
An adequate substitution for spackle is a column or caulk.
Note: Caulk jokes do not apply.
Not to be confused with joint compound.