You might want to just do a websearch. I've ordered stuff from  the guys below but I looked and didn't see anything around 6mm- only larger stuff:

https://www.fantization.com/

https://www.michtoy.com/

I would buy a $200 resin SLA/LCD 3D printer and make my own. At that scale the details would be minimal and the designs easy to make yourself. Plus you may find it extreamly enjoyable and creative.

These are some Japanese float planes I made in 1/450 scale for an IJN Mogami build. Their wing span comes in around a whopping 25mm though :)

Cool Joe, never thought of just printing them. 

https://www.baccus6mm.com/catalogue/WorldWar2/

I don't know for sure, but I'd be surprised if you couldn't find any such figs on Shapeways.

Have a nice day!

Paweł

I had to do a small bit-o-research,  6mm is equivalent to 1/285 wargame scale - GHQ stuff.   

I have dealt with Game Craft Miniatures who may appear as a sponsor on one of the sidebars on this site - or that is where I first found them.   I have bought some of their laser cut workbench storage items.   i am satisfied

they also sell 6mm/1:285 items; army packs and their own resin buildings & terrain.   Put Game Craft Miniatures into your google box and see what you find

EdGrune

I had to do a small bit-o-research, 6mm is equivalent to 1/285 wargame scale - GHQ stuff.

Ed stated the blinking obvious that I completely overlooked!

If the OP is new to the field, he may not know about GHQ miniatures. My guess is they have more different designs available than anyone.

https://www.ghqmodels.com/collections/1-285-6mm-scale