Slovenian spray artist Janez Jevnikar (a.k.a. Sprayman) doing sci-fi paintings in less then 10 minutes and he does not need expensive airbrush, studio, etc. Artist says: My studio is the street. I have worked with this painting tecnique since 1995. I use quicky drying acrylic varnish on a varnished cardboard, occasionally also on a Plexiglas and thin sheet. I also use a painting pad, paper, a sponge, pedestals and other material. Well, this looks really cool. See videos. You can find more about artist and his art on Sprej.com.
Spray Paint Art 2:
Spray Paint Art 3: