Depends... if you have access to a printer then that's how you can do it, for free.
You can use a site like
MPC to have them professionally (and rather inexpensively, I'm not a shill by the way) printed if you wish, and then there's the worst way, which I don't recommend, which is waiting for some shady bootleg sale on ebay where you'll pay a lot more and have no control over the quality.
Lots of options have been proposed. You can print them on actual cardstock, or cut out the paper and paste it to chip board from an old cereal box, or toss the front and back with a piece of card sandwiched in between (I've even heard of people using like bicycle playing cards for this purpose) inside a sleeve. Whatever floats your boat. I like to use glue-sticks for my tiles.
They said they wanted us to play-test this stuff, and they have to know mods will happen, so I can't imagine Hasbro being upset about it, unless you try to sell them. Just my personal opinion...