If you come across any picture tubes online anywhere and you want to use them as brushes, two things you need to know, providing you have Paint Shop Pro:
1. They have to have transparent backgrounds and can only be a single layer. I convert them from tubes into .png files, then
2. I call up Guillotine into Layers (found here:
http://registry.gimp.org/node/19886) and can be found in Image - Transform when loaded.
On occasion, I'll find some who actually upload their tubes online under the .png format. If Gnu Tux doesn't have a problem with it, you could add a topic folder for Picture Tubes that need converting from the .tub or .psptube format, and when I get time, I'll convert them into GIMP brushes. There are boatloads of picture tubes on the internet, of which many are exceptional quality and would make great brushes.
I tend to stay away from the general assortments, but I do find the seasonal and holiday tubes to be of great interest.
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"In order to attain the impossible, one must attempt the absurd."
~ Miguel de Cervantes