This time I made my own version of the magical heart collar you can see in the movie The Illusionist, completely desingned to be 3D printed. It's a romantic gift with which you can wear the picture of someone special and take him/her with you everywhere, but totally hided.
I printed it with Wood PLA (0.1 high layer and 100% infill is perfect) and it looks beautiful, but I recommend you to print it with a more resistant plastic such as ABS or PTG, or even the normal PLA. It's divided on pieces so you can easily assemble it by sticking them (I used super glue), but be careful not to stick the right side to the left one, because in this case it won't be able to work properly.
How to build it:
First of all, you have to print every stl file just once.
Each of 2 sides (left and right) are composed by 3 pieces: the top, bottom, and the middle one. You have to stick the bottom piece (the widest one) to the middle one, but placing before the axis (you can print it too: is the stl called axisbody with the axishead ) and a little spring between them (please look ath the pictures to see how it goes), just in the hole made for it . Then you must repeat the process with the other side. Be carefull not to stick the axis or the spring to the pieces that contain them: they have to be free so they are allowed to rotate with no problems. The springs (you need 2, one for each side) have to be 4mm long and 3mm diameter approx. I used the spring of a pen and cut it to get the lenght desired.
After that you should have a heart that, despite the fact it has got no front, it should be able to rotate and turn into a different form (to rotate both sides first pull of them in opposite directions). To collocate the entire movable top (toppieceL and toppieceR .stl), you have to rotate 90 degrees one of the sides until they are not composing either the heart ot the regular form, but like a kind of a cross. In that position there is enough space to place both sides of the front, finishing the magical heart. And do not stick any of the left pieces to the right ones! The only thing that keep joined both sides is the axis.
Hope you like it and if there is any question don't hesitate to ask me.