I tested out some terrain I made recently for WW2 at 6mm (1/300) scale wargames. I made some basic fields out of card, clump foliage and flock and I think they look pretty good. The trees were cheap on ebay and again on simple card base.
I also used some paper 1/300 buildings on a simple card stand – bought on Wargames Vault. The buildings look huge don’t they for a microarmor game! They’re quite nice buildings, cheap and easy to make so no complaints there. I have read that people often use 2mm or 3mm scale buildings for 6mm and I think I might go down that route in the future. I’m planning on doing 1 stand = 1 platoon rather than a squad so a smaller building imprint would make sense.