This is a gift card box where the recipient has to solve a maze to see what's inside. It adds a personal touch and some fun to the gift. There's a couple of different versions, depending on who you're giving it to, and how hard you want to make them work. If you use the 'open' top, the maze is visible and it should take about a minute to open. If you use the 'blind' top, the maze is not visible, and it will take a lot longer to solve. The cardtop part can have a personal message. You can visit the customizer page to create a custom message.
This requires some gluing, and likely some light sanding to make the pieces slide nicer. All the pieces can be printed without supports.
---- EDIT ----
I just uploaded a better slider to reduce the amount of sanding required. It is smaller, and has a beveled bottom to reduce first-layer-overprint issues.
This isn't very hard to assemble, but if you forget to file the slider, it could stick a bit, and won't have as nice of a feel to it.
You need to print five parts -- the bottom main section, the top of the main section, the bottom of the card holder, the top of the card holder, and the slider. There are several options for the top of the card holder and the top of the main section. One of the top of the main section shows the maze, the other hides it (and a third one has a guitar). The card holder top can be used with different messages (and you can customize it here)
Before you glue, you should test and adjust the slider. It should slide easily, but have little to no play on both pieces. Use a straight file or sandpaper on a flat surface, as if you round the edges you'll introduce play. You should also very lightly sand the top of the two tabs, to reduce friction. Clean out any burrs from the maze, and check that the pin slides freely through there.
If you are using the open model, with a semi-transparent plastic, you can use a permanent marker on the top of the pin, as it will be visible through the plastic making it even more obvious how to solve it.
Gluing is pretty straight forward. Use Krazy glue, and clamp for a few minutes before using. (dry fit before gluing to ensure there aren't any printing artifacts).
Once the glue is dry, insert the gift card, place the slider on the card holder (put it under the tab), and then work the pin through the maze to the fully closed position, and voila, you have a fun gift card maze box to give someone as a unique present.
UPDATE: I've put together 9 of these now, and I encountered a non-obvious issue so I thought I'd mention it -- if you find that it gets sticky right at the end (when you're just finishing closing the maze), then the cause is likely some rough edges on the top of the slider (not the top of the runners, but rather the top of the flat surface) and on the the card-holder top, where the slider fits. If you file these down so they're smooth it resolves the issue.