It is often said that one has an excellent command of a language when one is able to use it in an idiomatic way, which typically involves making use of Idioms and Collocations, i.a. There are many collections of Latin proverbs available but I'd be interested in taking a look at materials containing Latin idioms and collocations. Are there any published materials, dictionaries, etc. available? Do you know of any present or future project of elaborating a dictionary of Latin idioms? I cannot imagine the immense satisfaction of many of us if we could have access to online dictionaries of Latin Idioms and/or bilingual dictionaries of idioms (e.g., Latin-English/English-Latin).
More particularly, I'd be interested in knowing about idioms that involve body parts (NB: this type is quite widespread cross-linguistically/cross-culturally). For example, here is an example from Plautus:
nec caput nec pes sermoni apparet (Plaut., Asin. 729)
‘what he says has neither head nor foot’ // Cf. the Engl. idiomatic expression "can’t make head nor tail".
This class of idioms involving body parts is typical of colloquial usage in many languages (e.g., cf. also "to cry one's eyes out"). So I'd expect that similar idioms could be found in Plautus's comedies or in Cicero's letters, for example. Any other suggestion where I could find them?