ANY Doily design could be converted to this rug style; oval, round, square etc. Do it without a hook, just use your hands if you know how to crotch. As for heavy; just use the size cotton rope you want, doesn't have to be this heavy.
Crochet Rug Technique - crochet your mesh background then add rows of double crochet to the top. The different design possibilities of this technique are absolutely endless. What an interesting result!
How to Make Crocheted Rag Rugs | eHow These are definitely the most specific I've seen for instructions, they read like a pattern for folks who know how to crochet already. One of these days I'll pull my last unfinished rug out and try to finish the bleeping thing lol