When masking off oddly shaped objects masking tape can be a bit ungainly to manage. And using masking tape to create smooth curves is nearly impossible. These are great opportunities to use Silly Putty. Not only will it allow you to easily mask of odd shapes and smooth curves, it doesn't leave any kind of sticky residue. I'm not sure if it is available across the pond but it is widely available in the states and is often no more than a dollar.
One of the best uses for Silly Putty is for making organic shapes for camouflage.
Start by base coating your model in whatever color you want your camo patterns to be in. Remember that when masking the base color will be covered up in any areas you do not mask off. This is opposite of what you would do if you were painting on the camo pattern.
Once you have base coated your model apply the Silly Putty to the areas you want to remain the base color. Silly Putty is infinitely forgiving and can be applied, removed, and shaped as many times as you want. Once you have everything exactly where you want it, apply your paint.
I prefer to remove the Silly Putty while the paint is still tacky. This helps to prevent any paint from peeling, but limits the risk of smearing the paint. When you remove the Silly Putty go ahead and mix it up really well and you can use it again, and again, and again, etc. Eventually, if your Silly Putty ever wears out just toss it in the trash and get some more.
After you've removed the putty you'll have a beautiful camo pattern!
Don't stop with camo patterns, you can use Silly Putty to mask of odd areas when painting, use it to temporarily tack bits in place, as a bouncy ball, to make copies of newspaper articles and then stretch them out in wacky ways. If you have any tips on other ways for modelers to put this great tool to use please leave a comment below.