Not quite sure what the English spelling of tuches should be. The Yiddish is from the Hebrew: TChT (i.e., tav-cheth-thav). The Hebrew words in Yiddish are pronounced according to Ashkenazic (i.e., German) pronunciation, whereas Israeli Hebrew is pronounced according to Sephardic (i.e., Spanish) pronunciation. You can see this in shabbath versus shabbes 'Saturday, Sabbath'. The pronunciations are quite different: for vowels, consonants, and stress (accent). Cf. Seph. torah with accent on the final syllable versus Ashk. toyre with accent on the first, both meaning 'Pentateuch'. And, Seph. tachath is from a preposition tachat 'under, below'. So, I'd say the connection with thimble is unlikely. Though looking at Pokorny, I see that *teuk- coincidentally yields Old Irish ton and Welsh tin 'ass, butt'.