BAM (Better Arcade Mode) has now officially included support for Custom Pin-balls.
Thanks to Ravcade
To use these you need BAM - Better Arcade Mode (a Future Pinball MOD)
The latest version can be found here
In FP setup Please enable "dirt marks" to get new balls look.
After Bam have been setup, extract the packs to its directory.
C:\Future Pinball\BAM\Balls\ (Name of Ball zips here)
Bam now has ball pack function.
Default keys are "N" (Next) and "P" (Previous)
The custom ball is saved with per table settings (so you don't have pick every time).
These are free to use anyway you like.