If you have access to it where you are, Feria, you could use Milliput to create your flag. You can rioll it into very, vry thin sheets (that you then cut to the size you want) if you use plenty of talcum powder (baby powder) to prevent the rolling tool from sticking to the Milliput. The Milliput sheet can then be folded, waved and it will dry rock solid in a few hours. Then you can use decals to replicate the svastika.
Failing that, thin sheet of lead will do the trick as well (won't be as strong as the Milliput, though). Or the foil you'll find on top of margerine or yogurth containers or even around the neck of good wine bottles... A good excuse to have a drink!