Stateside these items [and suitable substitutes] are available at ‘big box’ [superstore] hardware/ home improvement stores - If you have nothing like that where you are, otherwise you may want to look around where construction trades and home repair guys shop for supplies.
Many of the items aren’t always available in the same configuration in the US either. I couldn’t find ‘grippers and had to make do with alternative arrangements. Grippers can be substituted with other ‘stiffish’ non-toxic rubber pieces of the correct size, then applied to the inside of the big Industrial Velcro with an appropriate opposite piece stuck to the back of the rubber.
"CableClamps" are used to bundle electrical cables together, if they are available at all in the EU, it would likely be at an electrical supply shop. You can also substitute reusable zip-ties.
Or you can simply take advantage of the efforts of one of your PE brothers and buy them here .
Luck and length.
WE are the 99% 'WE are the people you depend on; we cook your meals, we haul your trash, we connect your calls. We drive your ambulances. We guard you while you sleep. Don't f&ck with us'-- Madame DeFarge
"Rope trades @$10 a yard. I wonder if they even know that?"- Capitalist