I've tried egg shells, sand, the evil blue pellets and whilst on holiday at Center Parcs I even spent a fiver on a reusable bag so I could carry a huge bag of used coffee grounds from Starbucks back to the lodge (carried bags just weren't strong enough). Said coffee grounds were liberally sprinkled after planting our young cucamelons, cucumbers and pumpkins and next morning most were gone. I've cloched the very small amount left and still they got in one or two. I'm keeping everything crossed for my one remaining cucamelon as it was the one and only thing I really really wanted to grow this year. In the meantime I've planted some more seeds at home and hopefully we haven't missed the boat with them.
I scoured the shelves at Wilko last week in the hope of finding something, anything, I hadn't tried. Sheep wool pellets. £4.50 for a big bag. If it means I get to harvest something this year then it's £4.50 well spent. You make a barrier with them and then water which makes them expand. Apparently the idea is that they can't slime over them so go elsewhere. I may have gone overboard around my remaining cucamelon and given a very liberal application around my beans. Time will tell I guess. Next step scissors.
With the sheep wool pellets in mind I realised I had a wool liner from inside the packing of a Hello Fresh ready to take to the allotment compost heap. It didn't get that far. I tore it up and made little mats for my strawberries. Worth a try. Plus they compost down eventually.