I've been experimenting with combining laser cut acrylic sheets directly with 3D printing for a while but just now tried including TPU. And I'm glad I did because the result is a functional storage box that comes ready straight out the print bed.

What is it?

A simple stackable storage box that let's you see inside due to the transparent acrylic lid. It can be customized to any size or shape as the lid will be custom laser cut.

The process

The lid

First of all we need to have the lid handy when we start printing, so let's sort that out first.

There should be at least one workshop that can laser cut in your town because a lot of businesses need that service for promotional materials etc. Talk to them, they will probably be open to have a few pieces of 3mm transparent acrylic cut for you.

They usually work best on DXF files. The one I'm providing is in mm so make sure to mention that if you're in countries that default to imperial.

A thing to be aware of if you never worked with laser cutting, the laser has some width (called kerf), so the resulting edge of your laser cut piece will be slightly smaller than it is in the DXF. Half the kerf on each side, to be precise. For this particular use it's not a major concern (also my DXF compensates a bit for that), but it's useful to know.

Don't forget to peel off the protective film on both sides before printing. :)

PLA to Acrylic bond

In my experiments, some PLA filaments bonded incredibly well to the acrylic, but some were mediocre at best. I didn't narrow down any criteria to determine which will bond well, so you'll need to do a bit of trial and error.

When you find a good match, use that as the interface between the acrylic and other filaments with weaker bonds. (my TPU didn't bond as well to acrylic so I used some PLA layers in between, which worked very well)

Slicer setup

It's totally fine to have impossible overhangs in your print, ignore eventual warnings. They won't actually hang, they will really print on top of the acrylic that you'll place in.

Speaking of placing in, you need some filament changes:

  1. Can be just a pause if you're already printing with your well bonding PLA. It's the time to place the Acrylic panel in. If you're using a different PLA, you should also change the filament.
  2. As soon as the hinges start, we need TPU, so have a filament change here.
  3. The stiffeners on top are there to prevent progressive peeling of the TPU hinge, use PLA for those too.

Another relevant aspect are infills. We want the first layer that prints onto the Acrylic panel to be full perimeters to avoid the slicer wanting to bridge over the "gap". But then, the hinge needs to reset to 2 perimeters to be able to properly print the bendy part.

So in Prusa Slicer I used a full perimeter default and 2 modifier boxes to switch back to 2 perimeters:

  • one on the bottom to properly print the bottom of the box and not work overtime either
  • one after the interface layers, for the hinge and stiffeners to properly print

Reverse works too, 2 perimeters default and one 99 perimeter modifier box starting below the interface layers and ending before the hinge.

Let's print