Having a chance to ride on a warm, humid evening (for May at least), I took out this 1949 Raleigh Clubman that is set up as a light roadster.
This bike now has a front mudflap made from milk/water jug plastic. It is not difficult to make a mudflap from a milk or water jug. A template is traced on the large side of the jug, then the mudflap is cut out of the jug. Then you mark on the mud flap where the mounting hole should be and punch them out. After that, all you have to do is mount the mud flap using the fender mounting screws.
The nice thing about these mudflaps is they're made from easily-obtained material, lightweight, and work reasonably well. If the mudflap gets damaged or breaks, it's easy and cheap to replace. Here in the USA, the jugs generally are either opaque white or a translucent. Either will look good if you do a neat job of cutting out the mudflap.
Given how easy the material is to cut, the mudflap can be made in any shape that will fit on the side of the jug. I prefer a relatively small, tapered shape that is smaller than the stock mudflap that the old Bluemels fenders used. This shape gives a tidy, streamlined look that does not interfere with the motion of the pedals or the tire.
