I am trying to mount glass to metal, Answered

As for the metal parts, they look like furniture legs to me (upside down). Try Rockler or Outwater or even IKEA.

I think orksecurity has summed it up well. I've seen similar things to this which used clear rubber non-skid pads to keep the glass from sliding, and others that used clear suction cups.

Ask the people at the glass dealer.  They often have things or can get things that we don't know about.  There is a two sided foam rubber pad that the glass company used to pad and afix a glass counter top.

P.S.  You were planning using tempered glass weren't you?

I'll go with Ork', probably silicone glue / sealant. It's essentially "resting", the glue just inhibits the sideways movement.

L

Can't tell how it's done from the picture. The glass could be epoxied to the fittings (unlikely), it could just be resting on them, with some form of padding between the two (most likely, and simplest), or it could be bolted through (threaded opening in top of support, hole through glass large enough for a flat-topped bolt, washers to distribute the clamping force over a larger area, possibly some padding between washers and glass).