Canvas and Board blocks
When I first started out painting in oil I actually started big i.e. 5ft (1.5m ) wide and 20" (.5m) deep. I used to buy in a large roll of canvas and stretch it onto pine from the local builders merchant. The biggest problem with that was the quality of the wood, kiln dried pine warps.
To get round this I started buying seasoned tulip wood and I'd cut it to size using a cheap bench saw. Tulip wood is from the U.S. and is used by cabinet makers because of its stability.
Eventually I gave in and started buying ready made canvases from a company called Harris Moore who also use Tulip wood. It is expensive but at least I get the peace of mind that I'm not going to see a great string of unhappy customers complaining about bent pictures.
I still stretch medium sized canvases but buy in composite pine stretcher bars from Lion Picture Framing Supplies.
This is my Morso guillotine, I bought it second hand a long time ago. I can't sing the praises of this machine highly enough and if you get the chance to pick one up secondhand do so. this one was bought from a contract picture framers and had seen many years of abuse but it still keeps on going.
It allows you to cut a 45 degree angle to an accurate length and make making frames a doddle.
For small pictures I paint on MDF, I used to use canvas but the calluses aren't worth it. I make up a pine frame and the glue on a sheet of MDF. I'm very fortunate to have a friendly joiner who cuts up sheets of MDF for me into the require sizes