Sometimes, I want to use figures with cast-on bases in an army where most of the figures have square or rectangular slottabase-type basing.
For example: these Pumpkinheads, which have just emerged from my workbench. (The person who painted them wrapped them for shipping in tissue or paper towels prematurely, so I've been picking bits of sealer-saturated paper off the models.)
First, using my 3D base model, I print out a sample base to see if I've got the height right. I've learned from experience that at small sizes, printed models aren't always the size the original model specified! Here, I compare it against a convenient model, and decide to increase the height of the 3Dprinted base.
Generally speaking, I like a base that's about the size of the figure's extremities. Here, I've gone for 2" x 2" bases, with a height of 3mm. I also want to recess the middle of the base, so the cast-on bases aren't so obvious. Below, you can see a test print – recess is too small.
I tweak the size of the recess, make sure it works, print out four of them, and glue the figures into place.
The recess is filled with spackle (quick-drying putty). When the putty is dry, I spackle again to fill in any gaps or places where the putty shrunk as it dried.
Then I paint the top of the base brown, attach grass flocking, let dry, spray with a matte sealer, and attach a Litko FlexSteel bottom for magnetic storage.
Note that the Dullcote has also turned the unpainted 3Dprinted base sides from black to gray – that's a surprise.
(Apologies for not crediting the painter for these figures, but I lost that information in a hard drive crash a few years ago. If these are your paintjobs, please take credit!)