If you don’t gave a tap handy you can quickly “heat-set” threads in a part. Print the hole slightly undersized (I usually go 0.2-0.4mm under for M3-M4 size screws) so it takes some effort to screw in, then quickly screw the screw all the way in with a cordless drill. Friction should heat it up enough to melt the plastic and form it round the screw. Wait until cool before removing the screw. :)