This project was my first crack at using 123D Make to create something. Despite being a complete 3D noob, this came out looking pretty fantastic. The full-on release should be awesome. (I did cheat a little by stealing PenfoldPlant's 3D model to slice into bits, but y'all can scrounge up your own models when the time comes.)
The tree stands about five feet tall, and has a six foot circumference. It would make a terrible supermodel, but it looks rather nice as a tree. I made this for my girlfriend's cousin and her family, so I needed it to work or risk being "that weird guy who makes ugly Christmas trees." I think I succeeded in being "that weird guy who makes rather nice Christmas trees." I left them to decorate it, and I trust that it will come out looking nice. They have impeccable taste.
Feel free to download the .eps files and go nuts with your own tree. Resize to your heart's content.
Step 1: Print files/cut stuff out
I used a laser cutter because I have access to one. If I had to, I could have easily used a good razor and a lot of patience to cut the images out of cardboard using paper templates.
If you'll be cutting out by hand, maybe make a trip to the rasterbator to change the sizes, ensure that your tree is bigger than A4, and generally make your templates easier to manipulate. I didn't do any of those things - laser cutter, remember? - but you might want to try it if you're having trouble getting from the file to a template you want.