And here is the 3-fold view.
You can see a few gaps in this image, so my stl file needs a bit of
tweaking.
Now I've made a revised version in four colors.
I tried dying uncolored ABS, but it came out rather splotchy.
Here's another view of it, looking down a 4-fold axis.
The assembly solution steps are shown
here.
The stl file to make your own copy of it is available
here.
References:
This puzzle is in some ways similar to Geoff Wyvill's
Nova Plexus puzzle. But
these four triangles are concentric, while Wyvill's
puzzle is based on a different
orderly
tangle, with four non-concentric triangles. It is also very similar
to
Phillipe Dubois'
Kubion,
sold
by
Gaby Games, but its parts
do not overlap at the ends and so have only the two central
notches. Thank you Nick Baxter for helping me track this down and
for the
Kubion photo. Also
see Slocum and Botermans,
Puzzles
Old and New, p. 76.