When I first heard of this Christmas ornament competition, I wanted to create an ornament that met the following criteria:
a) Is light enough to be hung on a tree alongside other ornaments;
b) Doesn't require any special tools to be assembled (it's Christmas - you don't want to have to head to the store because you've run out of M2 8mm screws, and you want the part to be re-openable);
and c) Could hold a small gift inside (money, jewelry, sweets?).

I "present" to you: the Present Ornament! It is light enough to be hung on the tree, even with something inside it. It can be assembled using ONLY string, your 3D printer and a small snippet of extra filament. It's got enough space to hold jewelry, sweets, AND money (if you pack tightly).

This ornament comes in 4 pieces: the ribbon, the bow, the hollow body of the present and the bottom cover.

I've designed the ornament to be assembled in 3 steps:
1) Thread a string loop or a spare ornament thread (if you have an old ornament) through the ribbon, bow, and main body. You will need to tie the string several times on the inside of the main body to stop the string from coming out.
2) Insert your secret present into the present body;
3) Line up the present body and present base, then insert a segment of 1.75mm filament into the hole. Snip the rest off. Repeat for the other 3 holes.

Voila! Your present is complete!

Is your present heavy? Need some extra support? Or just struggling with the hole tolerances for the filament fasteners? Just print the STLs with the suffix "heavy payload", use a thick string or twine to thread them together in order, tie a knot at the bottom to secure it all in place, and hang it on the tree. No filament fastener needed!

Please do let me know if you see any possible improvements for this ornament. Good luck everyone!