Got some piccies of my Russky 203mm Howitzers with camo netting.
They're not as good as Troys 25lb'ers, but there again, what is?

The 203's are Heroics, so excuse the detail on them.
First piccy is a battery deployed on a hill:

With nets removed they look like this:

Close up with nets off:

Close up of a net:

Note that I made the nets out of a bandage from a First Aid kit just painted with Humbrol 155, a few dabs of dark green and a bit of flock on the top for leaves etc.
Once painted the material is fairly rigid but can still be folded easily and cut. I folded the material and glued it together in a similar fashion to a paper building, which it resembles in a way, being a bit square.
The net supports were made from a wooden lollipop stick cut with scissors and Copydex glued in. I painted them various brown shades to look like roughly hewn trees. Copydex is the UK name for a white glue that dries like rubber, but clear. I don't know if there's a US/Canada equivalent.
The earthworks were made from Miliput modelling putty and shaped by thumb print. A bit rough-and-ready, but I was just trialling to seeing what happened.
I placed the Howitzers in the wet putty to make track marks and painted these a darker colour.
So there you have it. Not brilliant, but a start.
Cheers,
Battler