Building floating and thermal insulating structures using only sand and electricity

This is to record an idea, so it is not patentable after this point in time (2017.07.18).
The problem is to create structures which float on water and/or have thermal insulating properties, and acceptable mechanical properties, while the materials used are cheap, and the manufacturing process is scalable. Use cases can include floating platforms, boats, off-shore or land accomodations, etc.
The solution is a closed-cell foam-like structure made of ordinary glass. The individual cells have small wall thickness, in the range where glass have elastic properties. The shape of the cells is “ridged” cube (or honeycomb) structure, where each plane have ridges in two orthogonal directions – thus the network of ridges forming a network in all three dimensions such that those ridges provide elasticity for the whole structure.
The manufacturing process is two-step:
In the first step sand is molten using laser, and pulled to create fiber.
In the second step, the structure is built from the glass fiber with additive manufacturing technique, using laser again.