A trowel is such an inexpensive tool, it’s hard for me to imagine making my own for anything besides the experience of making and having made it myself. Still, I can see why someone might want to make this one described by Instructables “PVC whisperer” Thinkenstein: It starts from ubiquitous scrap material, looks good, and is made using an unusual process that involves softening PVC pipe under heat (a delicate trick, safety wise) and forming it by hand.