I enjoy painting on a variety of different supports, but have found I quite like the firm and smooth surface that comes with a wooden panel. Cradling the panel also allows it to be hung without the need for additional framing and gives strong and sturdy result with a sharp look to the edging.
Buying ready made panels can quickly become expensive and you are locked in to standard sizes, but it really is quite a simple task to make your own.
Decide the panel sizes you want to build (it is more cost effective and time efficient to make a number at once).
Purchase materials to create the panel. For the surface itself I use a 4.8mm Masonite panel cut into the sizes I need, and for the cradle I use about 30x18mm Oak DAR Moulding.
Mitre cut the DAR to the length of the panel sides and clamp (using right angled clamps) and glue (using PVA wood glue) together.
Cut the Masonite panel into the required sizes. This material is soft enough that you can do this with a sharp utility knife.
Glue the panel, smooth side up, to the pre-made cradle and clamp / weigh down until glue is dry
Fill and sand the edges smooth
Seal the timber. For this I use a couple of coats of Golden GAC-100.
Gesso the panels. I usually go for about two to three layers.
Go nuts, these panels are ready to go!