Learn Farsi: همینی که سگک فلزی دارد، توسط استاد روی قالب شکل داده می‌شود. - This very one that has a metal buckle is shaped on the last by the master.

hamin is the emphatic demonstrative meaning "this very" or "this same". By adding the suffix -i, we turn it into an independent pronoun ("this very one") that acts as the head of the relative clause. The relative pronoun ke then links it to the describing clause, giving us "this very one that".

Is tavasot-e the standard way to say "by" someone in a passive sentence?

Yes, it is the most standard and formal way to introduce the agent in a passive sentence. While Farsi generally prefers active sentences if the agent is known, when you must include "by [someone]" in a passive construction, tavasot-e (by means of / by) or sometimes be dast-e (by the hand of) are used.

How is the verb šekl dāde mišavad constructed here?

It is the present passive form of the compound verb šekl dādan (to shape / to give shape). To form the passive, you take the past participle of the verbal part (dāde) and add the conjugated auxiliary verb šodan (to become), which here is mišavad. Literally, it translates to "it becomes given shape".

The English translation says "on the last". Is qāleb a specific shoemaking term?

qāleb is a highly versatile word meaning a mold, cast, block, or template used for shaping things. Depending on the context, it can refer to a baking tin, a concrete mold, or here, a shoemaker's "last" (the foot-shaped model used to build a shoe).