How about a 3 or 4 sided pyramid to be GTAW together... You could use whatever base metal available...
One can even incorporate a hidden entrance into the pyramid... It can be used as an ornament or paperweight so, consideration should be taken as far as the dimensions are concerned.
I'll check back with you when I find some more of the projects that I have for individuals. Btw, Lincoln eleectric via their foundation has a few project books available, and I have some of them available so, I'll look into them also. Check their website for more details:
https://ssl.lincolnelectric.com/lincoln/apdirect/store.asp?PID=16&cat=8Here's another one that has projects online from Miller Electric:
http://www.millerwelds.com/interests/projects/Respectfully,
Henry