The "Baby Boomer", a new pint-sized air cannon

Finals are over for me, but for no other schools in the area. To alleviate boredom, I took my air cannons out for a spin today. 
 Here's the newest addition to my air cannon arsenal. It's my third creation, created from the guts of the first and the spare parts from the second. Compact enough to fit in a backpack, but retains 2/3rds the power of the large (second) cannon.
 Little improvements are everywhere. Instead of a friction fit, epoxy laden schraeder valve I used a metal fill valve. It threads on, has a rubber washer on the back, and is epoxied in to seal any possible leaks. It's rock solid, and I have no fears of accidentally breaking it.
The parts of the Baby Boomer, compared to the old, long one. 1/3rd the size, 2/3rds the power.
One night I went a little over-board with a sharpie. Not only does it have a sweet logo, but I also used the sharpie on:
 Most of the ammo! Each has a unique face, and a...
 Tail number. Tail numbers help you ensure that you have all your ammo at the end of the day. After these pictures, I also added my phone number. I've lost a few of them, but because of the phone number people seem to be returning them.
 Me gusta face.
 Some sort of... Vampire shark thing. This was the first face, inspired by the A-10 Warthog nose paint. Please forgive the fingerless gloves, it's cold.
Some sort of starry-eyed smiling guy. A word of caution, if you shoot sharpied footballs at a white wall, the faces will rub off on the wall. I have a couple faces stamped on my room's wall right now. Now to go find a magic eraser...

Air cannons are great, cheap fun. After an initial ~$50 investment, you can use them for more or less free! Cheaper than going out on the weekends, that's for sure. If you've got a good head on your shoulders, consider making your own!

AK Stanag mag converter

During the summer of 2012 I designed a magazine converter for AK AEGs to allow them to accept M4 magazines. I sent it to my university's 3d printer to get a prototype made, and so far I am very pleased with the results! Almost all the tolerances are perfect. A second print, and it will be perfect.

Here you can see how the internals work. The M4 mags feed BBs from the front, and AKs feed them from the center. A curved tube allows the BBs to feed from the M4 magazine to the hopup. A cool little trick in solidworks is called "Shelling". You can take solid items, and create cavities within them. This comes in handy for saving weight, or saving material. In this case, I had to pay ~$12 per cubic inch of plastic. Shelling helped me cut the price of this part in half.
 When I found out I could add trademarks, I was incredibly tickled.
 Here the beginnings of the mag catch are visible. The ridges here are far too small, and the hole was removed before I printed the part.
Here's one of the earlier pictures of the solidworks file.
 This is a picture of the bath the printed parts are placed in after they are printed. Each part is printed out of two plastics. The first plastic is the actual composition of your part. In this case, it's ABS plastic - The same stuff Lego are made of. The second type of plastic is a structural support, brown in color. The structural supports are dissolved after the part is immersed in this machine for a few hours. During those few hours, the bath becomes very basic, and is heated.
 My part was placed in this little metal box to allow the studio attendant to place and retrieve parts without getting the solution on their skin.
This picture is the birth of my magwell converter, still wet from the bath. It is so exciting to see your work come to life. Nikola Tesla has a wonderful quote to describe it:
I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success . . . Such emotions make a man forget food, sleep, friends, love, everything - Nikola Tesla

Thanks for reading. I hope I have inspired a few of you to get something printed. Check your local university, or online.