Napkin holder

I didn't like that printing napkin holder in one piece introduce limitation to the pattern and even if pattern is possible to print in such orientation I didn't like how it looks. So I decided to experiment with foldable design.

Options

Use your own pattern

.step files without any pattern included, so you can modify them and add your own!

Use slicer modifier to expose infill as a pattern

Files with additional bodies to use as modifiers included. You can configure slicer to expose infill as a pattern. Example in PrusaSlicer:

Print settings

Main requirement is layer height should be at most 0.2mm so bendable parts has at at least 2 layers. In case of bad bed adhesion first layer 0.28mm and following layers 0.2mm.

Also I printed with ironing and 2 perimeters to improve final look of both sides, but it depends on your printer and filament.

Assembly

Folding

After printing “Side” part, you need heat bends (see below) and fold it, so from this:

it become this:

Bend heating technique

To achieve best results you need pre-heat bends. I started from bending bottom flaps and only then side one.

I found following options are suitable:

1. Use hair dryer. Apply slight bending force to bend and continue heating bend until it will bend almost by itself. Try to heat only bends, to avoid bending part itself. 
2. Use heat bed of your printer. After part was printed and safely removed from heat bed, set it temperature to temperature you used while printing (in my case 60°C for PLA) and pace parts on bed. Wait for couple minutes and then try to bend it. If you fill strong resistance, repeat process. It is not working as good as hair dryer, because heating is not localized to bends only, but it works better that no heat at all.

You try can use lighter to do that but I would not recommend open flame, because it can easily overheat plastic and also it can cover it with soot (ask me how i know).

Put together

Now when you fold both “Sides”, you need match and press fit “Base” into “Side” one by one, so you will have this:

It should keep together without any glue, but if you not confident, our your printer tolerances is better than mine, you can use cyanoacrylate glue to fix all parts in place.