You might be able to flip through thousands of photos on your smartphone or tablet, but there is really no substitute to holding a print. Hand someone a print and watch how they immediately engage.
This explains the recent resurgence of instant printers. They are portable, relatively cheap to purchase and maintain, and most importantly they are fun! So much that instant paper is typically among the top selling products on Amazon, especially around the holidays!
The other alternative is an instant camera. Although they can be as much fun, they are not well known for their flexibility and capabilities, especially when you own a bunch of other cameras! For one, the most exciting part for me is that I can take a picture with my camera or phone and send it straight for printing. I can also go back and print pictures from my library rather than only being able to print the last one.
Personally I am a big fan of the Instax Share range from Fujifilm since the very first SP-1, which used the mini instax film . I carried that everywhere with my Fuji X100T however I was left wishing for a couple of features. One was replacing the hard to find CR2 batteries with a built in battery, and getting the bigger Instax Wide papers. The SP-2 solved the battery issue and although the SP-3 didn’t quite it make it to the wide format, the square format was good enough to get me to upgrade.
That said there are many options in the market at the moment with Kodak, HP, Polaroid, Canon and others jumping on the opportunity. Pretty much every option out there seems to be around the 100 Euro/Dollar/Pound mark and paper is typically in the 15 Euro/Dollar/Pound mark for a twin pack which will give you two cartridges of 10 pictures each.