Levitating Christmas tree

EDIT (09.12.21): I have added some optimized parts, so Prusa MINI users could also print this Christmas tree :)

Materials

For this project you will need:

• Metal (or other material) rod/tube/pipe with a diameter of 10 mm and length of 75 cm - I recommend aluminium or brass one
• Some kind of string/rope (10 m should be enough) max. 2,5 mm in diameter (holes in the tip have 3 mm in diameter)
• All the printed parts
• Some ornaments to decorate your tree :) (optional hook model included here)
• A little patience in tying knots

Printing instructions

Materials used: PLA (Prusament PLA Jet Black and Opal Green) with standard profiles from PrusaSlicer, without supports. Print settings:

1. Tip - 0,2 mm layer height, 15% infill.
2. R1, R2 - 0,2 mm layer height, 10% octagram spiral infill + ironing for the top layer enabled (I think it suits nicely those rings).
3. R3, R4 & R5 - there are different possible options to choose from, depending on your printer size and precision (print settings same as R1, R2):
   • Prusa MINI: rings are printed in parts (copy R3 and R4 3 times, R5 - 6 times). But first, you should print tolerance test parts to check if they fit together (it should be tight, so you won't need glue). 
     • If test parts fit properly use R3_MINI (T), R4 (T) & R5_MINI (T).
     • Otherwise, use R3_MINI (L), R4 (L) & R5_MINI (L), which have more play between them. In this case, you may need to use glue. 
     • Remember about the right number of parts (x3, x3, x6).
   • Prusa i3 MK3 (or similar): 3rd ring is printed in one piece (use R3), while R4 and R5 are printed in 3 separate parts (just copy the model 3 times). Tolerances should be checked as described above in the Prusa MINI point - use [R4 (T) & R5 (T)] or [R4 (L) & R5 (L)].
   • Big printers with print area allowing to print 25 & 31 cm diameter rings - just use R3, R4 and R5.
4. Base - 0,2 mm layer height, 15% infill, Prusa MINI user should print the slightly smaller version (Base_MINI)
5. (optional) Hook for ornaments - 0,2 mm layer height.

Assembly

When you have all parts ready:

1. If you have rings 3, 4 and 5 in parts, connect them.
2. Put your tube in the base and then put the tip on the other end of the tube.
3. Tie the rings together using rope so they are connected. This is a hard part which can be done in multiple ways. I will explain my method below.
4. Places for knots are indicated on the rings by indentation on the bottom side. It keeps the rope in place and helps with alignment.

How to tie the knots (my way):

Thread the string through the hole in the tip - 3 times, every second hole, so you have 3 double carrying ropes (A in the picture). The remaining 3 ropes are purely aesthetic (B in the picture) - you just tie them on top and bottom (as shown in the photos). 

Double knots are located at points: 1, 2 and 3. Then repeat double knots in points 2 & 3 for other rings up to and including R5. Between tip and R1 you need 84 mm and then between the rest of the rings 112 mm of rope so it will look like in the photos. I recommend preparing 180 cm for each carrying rope (so you won't run out of rope while tying knots).

Happy printing and Merry Christmas!

// After Christmas you disassemble the tree by removing the metal tube from the base and tip, and the rest can be just put in the box, without undoing the knots (like in the photo).