I am preparing a workshop where we will make tensegrities.  These beautiful little mathematical decorations require (the way I make them) dowels with notches in the ends.  I made a special saw to notch the dowels on the spot, instead of notching a bunch of them in advance.  I just hope that people will be able to use them!

Here is a demo of the saw:

And here is an instructable:

http://www.instructables.com/id/A-saw-for-putting-notches-in-the-ends-of-dowels-b/

Here is the text from the same instructable:

This is the perfect tool if your crafts require that you notch the ends of a lot of dowels, but you don't have a band saw, or you don't want to be running back and forth to the ban saw. The cuts it makes are clean, and if you are careful with the measurements, you'll be notching the middle of the dowels.

One rule that I follow is:
Don't measure anything when you can square it up as you go.

The other rule is:
Don't measure anything twice if you can easily toss it away and do it again.

I think the pictures are somewhat self explanatory, so I haven't broken it down into steps.

The materials are:
-a thick bolt with a flat or round head (the type that go into wood)
-a long bolt. this will adjust the tension on the saw blade. see pictures for nuts and washers
-one thick washer which will connect to the saw blade.
-a coping saw blade (google this one, it's those extremely thin blades.
-4 thin bolts
-4 "thick" washers. These are your spacers around the saw blade
-some scrap wood, including a 2x4.

A drill, dremel tool and cut off disks is nearly indispensable here. If you don't have one and you are into this stuff, get one right away. I recommend grabbing a no name drill, but brand name (dremmel) bits. that way you don't care about burning out a $15 drill, but you have good bits to work with.

1. Put that thick bolt in and hammer it flat on the bottom so your saw lies flat.

2. Cut the bolt down to the right length.

3. Notch the bolt so the saw blade sits in it.

4. Prepare the tension assembly and screw it on wherever the saw blade comes to.

5. Cut a notch in the thick washer for the blade to sit in.

6. Put tension on the blade until it twangs nicely.

7. Prepare the guides that will keep the dowel centered on the blade.

8. Use the thick washers for spacers. Note that you can make an adjustable version of this thing, but I didn't need one.

9. Bottom bolts use the spacers, the top two bolts are just so the dowel doesn't run off the end of the saw.

Finally: To notch a dowel use a block of wood with a hole to hold it. The dowel should stick out the same amount as the depth of the desired notch. Enjoy your notching!

I got hopelessly lost the first time I tried to make this, but with a bit of patience and some images from the article on Wikipedia, I have come out of it one Compound of 5 Tetrahedra richer.

Here is an animated GIF of the model.  It will be available to buy on Etsy as soon as I have taken the proper photographs.

Each of the five tetrahedra is a different colour, so that the colouring has the same properties as the one in my coloured icoshedrons (correct me if I'm wrong here!).

I am available to teach people how to make things like this (though this one is for the nimble and patient), and I also colour sticks for such purposes.  Please contact me with the information on this website.

These vividly colored icosahedrons look great when hung from the ceiling, or a wall, but the fun doesn't stop there. You'll notice that the colors seem to follow a pattern which is quite amazing. 

I'll skip over the cool math that is involved, but try holding two opposite nodes still, and spin it by 1/5 of a rotation. What happens to all the yellows? All the greens? etc. Maybe I'll make a video about it later!

My icosahedrons are made using colored skewers that are held together with wire. It is not glued, but the whole thing is dipped in acrylic medium to give it a nice shiny finish. They are very durable and can be kicked around the house without breaking (don't try too hard though, ok?)

I will sell this by dutch auction, starting at $150, and reducing by $5 each week. You never know who's waiting for it to come down, so buy it quick!

http://www.etsy.com/listing/84895025/beautiful-geometric-sculpture-with

This is a "Hexastix", shaped into a "Stellated Rhombic Dodecahedron". It casts a beautiful shadow, and belongs in a sunny window where the light hits something behind it. You'll need to remember that if you buy it. :)

I make all of my sculptures in a small rented workshop in Victoria, BC, where I am a PhD candidate at the University of Victoria.

Beauty in mathematics, especially geometric beauty, is an ongoing passion. The asking price of this sculpture is very low, but it is worth selling, just to know someone else is in love with it.

Learn more about GeoBurst on http://geoburst.ca

I am pleased to announce the publication Japanese tatami mat tilings: No four tiles meet, in the Notes from the Margin, Volume II, 2011, from the Student Committee of the Canadian Mathematical Society.

The title of the newsletter comes from the story behind Fermat's last theorem.  He had written in the margins of his notebook:

it is impossible to separate a cube into two cubes, or a fourth power into two fourth powers, or in general, any power higher than the second, into two like powers. I have discovered a truly marvelous proof of this, which this margin is too narrow to contain. (wikipedia)

This article is a condensed version of a result in the conference proceedings: A. Erickson, M. Schurch, 2011: Enumerating tatami mat arrangements of square grids, in 22nd International Workshop on Combinatorial Algorithms, University of Victoria, June 20-22, volume 7056 of Lecture Notes in Computer Science (LNCS), Springer Berlin / Heidelberg, 2011, p. 12 pages.

Abstract:

Tatami mats are the type of mats used in traditional Japanese rooms. Often, an arrangement in which four mats meet at a point is considered unlucky, perhaps because the word “four” sounds like the word “death” in Japanese. So, a “lucky” layout has no “+” shapes formed by the lines where mats meet. Compare the following two arrangements.

Tatami tilings are accessible and fun, so go ahead and take a gander!