So here's the garage/speed shop dio I've been cranking on for the last 5 months. I just signed up for the forum about a week ago so I'll just post everything I have, from beginning to where I'm at now.
I started with a garage kit that was given to me after a friend gave up on it and went from there.
To start, I cut some scrap plywood to size to fit the shelf it will be displayed on which was then painted flat black. I masked off where the base of the garage would be and sprayed the surface with Rustoleum Multi-color Textured paint which turns out is pretty much asphalt in a can.
When the "asphalt" dried, I went on to make an area for a junked 34 Ford pickup I'm currently finishing. It started with a quick coat of burnt umber acrylic paint, followed by a mix of flour, water, fine sand, brown and black paint, and Realistic Water to simulate mud to the best of my ability. After the mud dried, some gravel, grass, brush, etc. was added. It still looked a bit bare so I raided the girlfriend's spice cabinet and made a mix of basil, oregano and thyme to make some natural ground clutter.