TLDR

I always wanted to create an endlessly expandable modular box system which uses very few parts and needs only very little material to print, but is still stable and useful and visually appealing. With that feature set and so many restrictions I guess the assembly time is a good trade-off, or if you enjoy 3D puzzles then you might enjoy it. Yes, this is a warning, don't expect this to be an easy, one button print and ready stuff, it takes much more time to plan and assemble than printing it!

The strips are pretty strong if your first layer is well calibrated and the'll be standing still after the full assembly.

Preparing for printing

Planning

If you decide to give it a try, then first you should draw a few sketches and then count all the strips, towers, connectors that you'll need.

For example in a simple 5 sided (top open) box with all walls 5 units and two colors, you'll need 12 pieces tower5 elements, 8 pieces corner connectors and 2x25 strips5 from each color. So that is already a 70 pieces puzzle.

Printing

First layer calibration is a good idea to have a good quality strip printed.

You'll need a bed scraper to get off the strips from the bed, just leave it to cool down.

Printing is straightforward, on my Prusa with satin bed I needed brims for the towers, but you might be fine without them. Tolerances on the connector are permissive enough to not to be afraid from the leftover of the brim and they will be hidden at the end.

Assembly

That's the hardest part, but also that holds the most fun. If you really enjoy puzzles then skip this part as it contains a lot of spoilers.

Strip sanding

Slipping in the strips to the tower slots might be a bit hard at the first (or it is just a calibration issue on my printer), but if you hold the strip tightly and close to the tower, then you can move it up and down two or three times and it gets “sanded”. I recommend to take one tower and do this for all the strips you have on both sides. Yes for the example simple box you'll doing that move at least 280 times.

Wave up your container

So now you are ready to use up all your strips and build your container. Without the connectors it will be very mobile until you wave up all the walls and then it starts to get its shape.

As you can see there is only one tower where the strip bumps can enter, so each strip will connect to two towers, but the towers will be aligned in the opposite direction. So one is receiving the strips from the top and the other from the bottom. By the way this will help the whole thing to stay in one piece during the assembly.

You'll soon face the situation that you cannot assemble multiple bigger parts together, but you have to start from one point and then expand that gradually. There are situations where you would need to slide in multiple strips to the same tower in the same time. This is the third picture above, the vertical tower was slipping to the strips from the bottom. I never said it would be simple, but if you are already here try to enjoy the puzzle!

Attach the connectors

Before attaching each connector, please do a favor for yourself and check if all the woven patterns are correct, this is the last time you can fix it!

Connectors have a full circle and some halves. The full one should point towards the center of your box and the halves should cover the other connecting towers. So if you start from the bottom then the full circle should be on the top.

Start from a bottom corner, that is the easiest and glue the full circle to the tower, you'll only need a drop of superglue. When the glue dried move away the connecting towers a bit as it is still very flexible and put a drop of glue to an other tower (one at a time) put back to its place and hold until it dries. Repeat this for all the remaining towers (on corners there is one left).

Do all the other corners. It will be easier if you do one that has a connector already on the other end of the tower.

Inserting wall and cross connectors are a bit harder as the strip length is pretty precise. You have to apply a reasonable force to slide them in place. Unfortunately there is such a force that can tear the strips, so try to increase the power in small steps. It is possible! Gluing might not be needed at all here, but I recommend to use it on the full circles.

License - attribution - the strip concept

As the model license states you should not remix these files, but it is because they should be generated and I'll put up the code so you can generate them.

I am proud of the idea of using a one layer foil to build up the walls, but it is in common knowledge. It might easily happen that for 3D printing it is not a novel idea. However if you create something that is based on my idea, I would be happy to see some attribution, maybe linking to my model.

Fun facts

The whole model was created with the awesome Replicad software and the whole code is not even 100 lines. It is fully parametric so 10mm strip width or any tolerance changes would be just a nobrainer to change. I plan to release the code soon, I just have to clean it up and that won't be ready before the contest deadline.

Even if the model looks simple, this is the 5th iteration. I experimented with many solutions for the towers and connectors to be glue-free, no success till now. A good design tip: even if you have something that looks like will work and you try out in small that would not mean that it'll work on a bigger scale.

Did you know that superglue can be “washed” from your hands with citric acid and water solution? OK, you'll have to bath your fingers for 10-15 minutes, but it works!

Can you spot the mistake in the pattern I've done on the cover photos?