The Making of - trash bags:
This picture shows all what is needed: plastic wrap (from the kitchen), some thin wire and something to fill the bag with, I use ballast.
I cut off a piece of plastic wrap and put some fine ballast on it, this determines the size of the bag later.
Now I'm forming something like a "bag" by pulling all sides up, the ballast stays in the center.
The bag is closed by twisting it against the rest of the wrap. This should be rather tight.
That's the result - next is to fix this with a wire.
The wire should have two or three turns, closely to the filled bag.
The wire is fixed by twisting it. Since I do not want the bag to spill its contents on my railroad, I use some pliers for twisting the wire really tight.
That's the result; the wire is still way too long, but this makes the handling easy.
Trash bag with a coat of acrylic primer - and now it's time to cut the excess wire.
The bag can now be colored as desired and weathered, finally glued down. I use CA - and have to glue it down twice: When glued down for the first time the bag is easily removable because the CA sticks better to the color then the color to the bag. So I remove the remaining color from the ground and glue down the bag a second time, now with direct contact of the CA to the bag - and that's it.