Medium-density fiberboard (MDF) makes a good (and cheap!) support for painting and drawing. A 4′ x 8′ piece from a lumberyard is $20. That is 40 9″ x 12″ panels for less than .50$ per panel.
If you don’t have a table saw, you can buy a pack of 12 pre-cut panels for 1$ – 3$ per panel–still a good price. The only issue with the pre-cut panels is the limited availability of sizes.
This photo shows the first batch of MDF panels. The 4 gesso’d panels are from a pre-cut pack of 12 I ordered from Blick. Two coats of acrylic gesso and they’re good to go. They’re ideal for oil studies, gauche sketches, or pen and ink work-ups. In the past, I’ve used them for charcol drawings too.
Note: To prevent MDF panels from warping, it’s good practice to gesso all sides of the panel.
For oil sketches, I do an acrylic sketch and then finish with oils. 2-3 sessions total–quick for me! The panel with the landscape on it comes from a large section of paneling that I cut into usable-sized pieces. The photo above shows the work after 2 sessions; 1 acrylic, and 1 oil. I’ll finish it in one more session with the oils.
Here’s an oil painting on canvas in which I followed the process described in this post: rough-in with acrylics and finish with oils. For those interested in such things, this painting is old (20+ years) and doesn’t display any surface issues, like cracking, related to oils over acrylics.