Add freeform building (less blocks, endless shape possibilities)
It's possible that SE is in such state that this would require too much work but here's the suggestion anyway.
Right now SE lacks many block shapes and KEEN doesn't seem to be interested in adding more. Freeform block building would decrease the amount of blocks a lot and make all those missing triangle blocks possible.
This could even make small grid window blocks possible =D
Skywanderers are implementing this and it would be awesome in Space Engineers
Weight could be calculated from the volume and material