Read this post and make you own conclusion... For the first I would say go for it....
http://www.cnczone.com/forums/showthread.php?t=49251 (newbie: plywood or mdf?)
I'm about to make my first CNC (JGro) mill . I wonder if i can use plywood instead of MDF since i can get the plywood needed for free
i was thinking about using 18 mm (0.709 inches) for my first mill ..
have anyone tried to use plywood instead of MDF ?? and will it work ??
Worst case is you will build a machine to build another.... second is much simplier...and Yes it will help to paint it and may be just fine for the purpose you need it for.