Yes, the heater/filter intake is kind of DIY, more like 'cut-it-to-size' kind of deal.
Is the plastic material they use to wrap the lower part of tree saplings when they are first planted in parks, neighborhoods or kind of big tree planting situations. I am uncertain what the purpose is, whether protecting saplings from deer or people walking over them, but they use it often. I am sure you have seen them around. It is tubular, rigid, and it is fully plastic (I have seen other types which have a metal core).
I use it for heater / filter intake guards, but my initial intent was around the intakes, to prevent long (tall)-leaved plants to getting sucked onto the intakes. Using these guards, it becomes possible to have long and wavy fronds, next to a comparatibely powerful suction (AC 110, Fluval FX6), without an issue.
The material is insanely expensive from commercial sources (I looked it up), and comes in humongous rolls. I was able to get a small piece from a friend, left over from a nursery. I now have pieces of that in several tanks and love it!