Making a firearm - legality?

I'm wanting to make, with proper materials and tooling, a simple, break-open, single shot carbine to fire 7.62x25 Tokarev or 9mm (pistol cartridges). I'm 18 years old and I live in Texas (where nearly any gun is legal). I this legal to make without any license? Also, any tips or warnings on making this would be appreciated.