Polyethylene comes in at least 3 main types
LDPE is soft and often used for plastic bottles you squeeze to get liquid out. it is more rubber like and the least brittle or least likely to break.
HDPE is moderately harder and is used for milk bottles. More rigid but still moderately flexible
UHMWPE or ultra high molecular weight polyethylene is a hard plastic that is much less flexible. some types with graphite fillers to make them electrically conductive or static dissipative do not bend far before breaking. so this plastic is rarely bent 90 degrees in a sheetmetal brake. it is often used as a teflon substitute as it has almost as much chemical resistance to most chemicals that teflon will resist. we use UHMWPE to make parts before making them of metal for testing purposes. plastics that are moving near other objects can develop an electrical static charge. this charge can be dangerous and the reason for additives mixed in the plastic to make them electrically conductive to prevent charge buildup.
....... you should be aware that Polyethylene does not glue easily because it is chemical resistant. it can be welded with plastic hot air welders.
cutting tools. i use tools made for cutting aluminum with a high helix and positive rake. the sharper the better. i use tools like end mills that have never been used to cut metal because dull tools will cause a poorer finish and raise more burrs. in general cut as fast as possible but not so fast as to melt the plastic. we cut sheets on a woodworker table saw but be aware that a dull blade will overheat plastic and cause binding when cutting.