A friend of mine just finished one. She just made two squares for the outside and two squares for the inside lining. She used the boy's grandfather's ties (GF died 2 yrs prior), and fabric from other predecessors. The lining - one side she embroidered "Made with love by Aunti Carol" and the date, or something like that. The other side she embroidered (she has an embroidery machine) "Remember those who came before you" and the names of everyone whose items she incorporated into the bag and tallis. She texted me this morning that she just finished it! I think she was going for about 12"x14", enough room for a clumsy 13 yr old boy (it's for his Bar Mitzvah) to still fold the tallis and fit into the bag. It has a zipper, but not on the top seam. My friend is quite an accomplished seamstress, she came up with the pattern by herself. I don't imagine it could be that difficult, just give plenty of room for the tallis. I made some once and made them too small - AWKward!!