If anybody wants to make one like the DIY one, use blue barrels, not white. I've found that the white barrels get brittle over time, where I have not seen that with the blue barrels.
I have polypropylene white barrels that have been in the sun for a number of years, and no ill effects, unless you cut the top off and use it as a water target for some .44 Mag stuff, then the bet's are off. They tend to leak a bit after that
The Blue pigments probably have some carbon black in them, so that would slow down degradation to UV exposure.
