Glass is a remarkable material, it is crystal clear, comes in a whole rainbow of colors, and can be shaped in a wide variety of ways. Stained glass is made entirely cold, so is the most predictable way. I made the below piece in the winter of 2023, representing the duality of the cube and octahedron, from a vertex-perspective. The frame was especially challenging to make, as there were no right angles! With a jig, and the help of my father, we cut framing board and supports at the requisite angles / lengths, and screwed the frame together before staining it. 
I have also played around with lampworking, it relatively cheap to get a torchead for a MAP-gas canister and some glass rods, though it is quite challenging to work with the variable viscosity of molten glass, pulling and shaping the material. This setup is also limited to smaller pieces, as it does not produce enough heat to work borrosilicate glass (which is less likely to shatter) or large pieces. Lucas Clarke is a fantastic glass-blower, who makes Klein bottles! I also really admire the work of Anduriel Widmark who uses a torch to bend clear glass rod into dazzling mathematical objects. 