That is virtually impossible at this point, I'll elaborate.
1. There have been over 100,000 downloads of the magazine. If you ban it from public download, it'll simply be spread via e-mail. If you somehow make it impossible to share by any means of online communication, the information can just be shared physically via thumb drives, CDs, etc etc.
2. The knowledge to build a basic 3D printer has become too wide spread. Case and point, a boy in Greece made one out of lego.
You can make a 3D printer with a glue gun and a couple stepper motors, with surprisingly good results.
3. The tools to design these magazines are free and widely available. If this mag becomes banned somehow, someone else will just make a new one, and that action could be repeated infinitely.
When a government has the level of control that is able to prevent the sharing of such knowledge, it'll be a very dark day for us all.