Craft
Origami
crystal vase
I draw a scheme for this just for fun. It was eventually published in some origami book in Rostov.
Menger's sponge
We made it from thousand something Sonobe modules (yeah, I am surprized that it has its page on wiki). Better with glue.
My random models
5 tetrahedra in a dodecahedron
Another beautiful thing by Thomas Hull. See instructions at this page. I use this thing to explain why the proper dodecahedron group is isomorphic to A_5.
Curlers
Curler is a great thing: you only need a polytope with degree of each vertex equal to 4 and a waterbomb base. And some thin tool to make waterbombs curly.
Not origami
What a time to be alive
I was surprized that I can simply buy a cheap clock mechanism in a creative store and draw whatever I want. Its already 15 years, and they still show time at the parents' kitchen.
New Year
A budget solution is to make new year "balls" from glow-lamps. We had a great time boiling lamps to detach the glass from the base. In the end, we realized that buying ball blanks is easier.
Math models
Some models crafted from paper and plastic as the follow up to my papers [18,21] in this list. Used for demonstrations when grass was greener and the talks were held offline.
Halloween
That's an eco Jack-o'-lantern which preserves the world's population of pumpkins. One pumpkin, 5 faces.
Cooking
Japanese food is great, but after one year in Osaka I started missing some Russian dishes, so I learned to cook. Go find the Hopf dumpling!