As long as you're not going to sell it, go right ahead!
Neato! I'm only wanting to make a set to play with, and since I've got a lot of blanks in the order, I figured I'd fill some out.
On the subject of printing, be advised that there are TWO sizes of cards floating around: there's the standard 2.5"x3.5", which Horrible People used for the most part, and the slightly smaller 63mmx88mm, which was used by most of the vendors at BronyCon this year (including Core Deck 1.1.6). If you use card sleeves, it's not a problem.
Well, as much as I've played card games across... oh, it's got to be 15 years of my life by now, I've never actually used card sleeves. I've always treated my cards carefully (even shuffling without that bendy technique -- that makes me cringe whenever I see someone do that). Right now the plan is to order the cards from the site linked to from HPG's site, though I'm not sure offhand what size that is. It says "poker cards", but I've never actually played poker, so *shrug*
Also, we'll be releasing updated versions of Extra Credit and Ponyville University soon, so you might want to wait for that.
I expected that, but since I'm not sure when "soon" is, and NMM is just over a month away, I figured I'd print out the 1.1.5 core deck and current versions of everything else, then when you've got updated versions, print those out too and either have shenanigans or simply give someone else the gift of shipping.
Oh, and thanks for the quick response! Super-glad to hear back from people after just joining a few hours ago.