Ryanair might require you to print your boarding pass (depending on your nationality you may be able to use the mobile app or not)
I didn't find any print shops in Venice, can I print it myself in the airport ?
You actually can ! They installed a self service computer with print machine. In front of the Ryanair desk, on the right of the escalator.
We tried to do this at Treviso Airport 21/5/17. Extremely frustrating!! First machine didn't work. Second machine extremely slow so that you think it isn't working! we put in one Euro which was gone before we connected. Then put in the credit card with a minimum of 10 euros. There is no @ on the key board. So to enter your e mail, for @ you enter " alt+64"- go figure!! We eventually got the boarding passes on the screen but then couldn't print them. I think because it costs 5 euro per sheet of paper and we were down to 3 but not really sure. No Ryan Air staff anywhere to assist. The girl on the airport information desk is obviously used to fielding questions about this STUPID!! system and said that the checking in staff would accept a screen shot which they did. So allow plenty of time and don't bother with coins, just use your credit card and be prepared to pay.