struggles to complete his SISI truck force.
Spotted this in one of the local Dollar Tree stores, in the craft section:
As you might guess, it costs $1 USD, and you get six hexagonal wooden pieces.
The pieces are one inch from flat to flat, and 5mm tall including the magnet on the bottom.
If you're looking for hexagonal bases, these would obviously do the trick. In fact, they're the same size as Heavy Gear bases (well, slightly taller due to the magnet), and you don't have to fill in the slottabase!
The only bad news: These aren't listed on the store website, so they might be on the way out – get them while you can.