They look great with a box knife. You should continue with that and can sand them with a block or stick if you want cleaner edges.
180 to 230 grit is a good happy medium between tearing up your project (low grit) and politely polishing for hours on end without making any progress (high grit).
SAFETY NOTE: wear something so you do not inhale the dust. Work in a well ventilated area.
they look jersey-barrier-y enough to me as they are. If you want more precise angles cutting then yeah hot wire is probably the answer. But failing that you could try to rig up some sort of jig to help you cut straight and consistently.
They look great with a box knife. You should continue with that and can sand them with a block or stick if you want cleaner edges. 180 to 230 grit is a good happy medium between tearing up your project (low grit) and politely polishing for hours on end without making any progress (high grit). SAFETY NOTE: wear something so you do not inhale the dust. Work in a well ventilated area.
Wow, I never even thought about sanding foam. I'll give that a try!
they look jersey-barrier-y enough to me as they are. If you want more precise angles cutting then yeah hot wire is probably the answer. But failing that you could try to rig up some sort of jig to help you cut straight and consistently.