DIY star fire tank

[Nizzmo]

Hi there. I recently found out me neighbor works at glass place and can get me edged, tempered star fire glass @ $2.80 a sq ft and I'm interested in building my own tank. I'm terrible at DIY so I would like to over research this.

My goal is a rimless braceless cube with an overflow in the center.

I'm thinking 16" high and 30" x 30" square.

What think ness would I need to support a rimless braceless design?
How would I attach the glass pieces together ? If silico is suggested which brand will be strong enough to help me achieve this ?

He says he will drill holes for me for free as well.

Your input is much appreciated. Thanks