We rent and our kitchen was fitted decades ago by someone with neither skill nor sense. In one area, at the corner where the worktop going across is joined to the piece going lengthways, instead of joining it properly there's a gap where the curved bit that would face forwards is butted up badly against a flat raw edge. So the top of the worktop has a gap about 4mm where crumbs constantly fall down. I initially stuck a bit of cardboard in the gap just because it kept making my plates dirty! I'm guessing some product exists that will nearly cover this gap but no amount of searching seems to find the right thing.
Any ideas?