Sammy the Flexi Sea Urchin

NOTE: All print profiles have been updated with an improved clip for holding the parts together as of 15:10 UTC 12th Nov 2025.

This is a flexi sea urchin, in a similar style to my other flexi models such as the starfish, except this one is not a flat model.  Instead it prints flat, then you snap various edges together to make the ball-like shape.  It results in a very satisfying model that is extremely tactile.

For a quicker print, Sammy now has a smaller brother, Barry the Baby Flexi Sea Urchin, that might be more suitable for smaller hands, or if you want to print lots of them at once.

There are three variants here, one with short spikes, one with spots, and one with an open top to the cells so you can see through it.  The models are surprisingly robust, although perhaps avoid the variant with spikes if you are going to be very rough with it.

I used Bambu Labs PLA Basic for all my prints.  The models only have colour changes at layer boundaries, so if you don't have an AMS and want a multi-coloured model, then you can use Bambu Studio to add the appropriate pauses.

The models snap together quite easily under finger pressure although it gets tricky for the last few joints where you can't get your fingers inside to support and align the parts.  To make that easier I've included a pair to pliers on the second plate, specially designed to fit the cells.  Put the two halves together as shown below, and optionally add an M4 bolt (or bent paper clip or whatever) if they tend to come apart during use:

Now you can use the pliers to squeeze the two halves of a cell together:

Assembly

The Sea Urchin model prints in two parts, purely so that it will fit on smaller build plates.  Align the two parts on a flat surface as shown below and squeeze together the halves of the two marked cells.  They should snap together with a little pressure.  If you find this difficult you can pick the pieces up and optionally use the provided pliers:

That gives you the shape shown below. Next join the two halves of the four marked cells:

You now have the shape shown below.  Again, join the four marked cells.  You will have to pick the model up join these:

Now you have the shape shown below.  Again, join the four marked cells:

That gives you the shape shown below.  Next join the two marked cells:

What you have now is effective a small flexible bowl with a lid:

Simply work your way round the sides of the lid, joining them to the body of the bowl.  This will result in a flexible ball shape.

That's it!  You have a flexi sea urchin to enjoy and amaze your friends with!