Perfect loop is very good , really prefect, for uncoated grids. But when you use forvar coated grids or or slot grids, perfect loop may damage formvar film because its flattened rim is too wide. You can make loop from thin metal wire 2.5-2.8 mm in diameter by youself, it it will be better for formvar film.
I have made my own wire-loop tools to use but I find that when I try and use them to load thin sections onto my slot grids, the two grids stick together and I have a whole different mess. I am able to coax my sections onto formvar grids pretty reliably but there is always a chance to lose sections due to the difficulty of the task.
For coated/slot grids, usually, people use the "tide" technique. You dip tour coated grid in the water of your diamond bucket holding it with tweezers, place the grid below the sections and gently lift it up so that the sections/ribbons stick to the lumen of the slot grid. One can use an eyelash to force the ribbon to stick to the formvar film first.