Today I built some tool tubes to mount on the Suzuki DR 800. The construction went well but the paint not so much as the humidity meant that the paint hadn't gone off by the time I wanted to mount them. Not to worry, once they are fully mounted and test, I can take them off and repaint on a drier day and let it cure for longer.
They look OK here and you can see that they will mount nicely on the DR grab handle. AT the bottom photo you can they are just 90 mm PVC downpipe. There are plenty of website on the Internet on how to do this but really, it just takes time and imagination.