I decided to recycle some materials to create home made canvases a while back, but I never shared it here, so here I go
Here's what I used. An old shirt for the surface and pieces of foamboard for the frame
Cut a piece of board and a piece of shirt. Glue the two together with matte medium mixed with water.
Prime the surface (which I actually didn't do here XD) and paint away!
The final result painted from life... mostly...
And here's a recent one I did a day or two ago on a properly primed one. The surface worked surprisingly well once primed properly. It's kind of similar to a canvas you can buy in stores, but a little bit smoother in texture.