Overall your sketches work, I like the scissors sketch, it is simple and communicative. The cut-section lines work very well if they are done precisely. Your designs are a bit generic, see if you can brainstorm a bit more and develop your own design language into the products you draw.
Your glass rendering needs work, start by studying the basics and drawing from perception. In reality, refractions behave quite differently and there is a logic to it enhancing the 3D-aspect of your drawings, if you can catch it.