Shop class was fun.  We made things from wood, wired a lamp, fabricated items from plastic, wood and metal.  A really fun class.  It taught me two very important things.  One was a fascination with words; in particular, the words transparent, translucent and opaque.  The assignment was to make an item from plastic.  First draw the items, I chose a candle holder and a letter opener.  Then we had to chose the material.  So many choices and the plastics were in a variety of colors and some colors were more transparent than others you could see your hand through them and that varied the outcome of the project since gluing one or more of them together could make two or three transparent items opaque.  Loved those words.  For the letter opener I chose cobalt blue translucent plastic.  A thin narrow piece so not much cutting was required but more shaping.  After the rough cut came the abrasives and refining the edges.  I started with harsh, coarse abrasive sandpaper and kept at it each stage changing to a finer and finer sandpaper.  The material started to gain more polish with each reduction in coarseness.  Finally a paste with a rag for the final polish.  A beautiful translucent cobalt blue letter opener.