MementosG 40

Mementos G40:
Complete three different collections.

Easiest way to get this is to always play on the highest venue you have unlocked and only using your keys on said venue. The higher the venue, the more coins, tickets, and keys you can win, thus allowing you to build up your stock and stay in the game until you have blacked out all boards. In doing so you will end up with 50+ chest at the end and will end up with at least 1 or 2 pieces of a collection while you are trying to level up and unlock the next venue.

Once you hit level 46, just go back to the venues you have the fewest pieces remaining and grind till you get all 10.

ALSO, if you have already gotten this on the Windows 8 version, it will pop as soon as you start the Windows 10 version.

Credit goes to MiniHorseRodeo

Luggage you have opened will occasionally give collection items at a relatively low drop rate. My suggestion is to continue working on a single location until you have completed the collection, even if later locations (and therefore more xp/$$ profitable locations) have opened. Don't move on to the next location until your collection is complete. It's a long grind to level 30 so this will give you a goal to focus on in the meantime.

Once you have completed a collection, move on. Early on, I mistakenly thought that I could begin working on the second tier of a collection once the first was completed, but this is not the case. You cannot come back around for the second tier of a collection until you're something like level 51, so collection items will stop dropping once you've completed the first tier.