There is always stuff sitting around to offer cover or to hide behind in our real world. It is also a good thing to add into your terrain selection for any miniature games you might play.
I have put together a number of boxes and crates to add to my collection. These will work for both 15mm and 28 mm games.
I went to my local craft store and bought a couple of packages of square blocks. I think the 4 bags I got cost about $10 total.
I used some wood glue to make little clusters of these crates. After the glue dried, I painted the blocks a variety of colors. Some were pretty bright but wasn't worried as I would be dulling the colors with a wash.
Finally, I used some MinWax as a wash to dirty these ups and to tame the bright colors.
You can see the group of my new terrain. This will offer lots of cover for my troops to hide behind.