Here is your short paragraph on Visvakarman Puja:
Visvakarman is the divine architect of the universe, the personification of creative power which ‘welds heaven and earth together’.
Visvakarman not only represents supreme creative power but also universal knowledge and wisdom. He is both the establisher (dhatar) and the disposer (vidhatar). Satapatha Brahmana (XIII. 7, 1f) mentions that Visvakarman performed a universal sacrifice (Sarvamedha) in which he offered up all creatures and finally himself.
This sacrifice was believed to be particularly efficacious and to give supremacy over all creatures. This ‘dismemberment of the lord of creatures, which took place at that archetypical sacrifice, was in itself the creation of the universe, so every sacrifice is also a repetition of that first creative act.
Thus the periodical sacrifice is nothing else than a microcosmic representation of the ever-proceeding destruction and renewal of all cosmic life and matter. But Visvakarman’s importance was superseded by the notion of the eternal Self-Existent Principle (brahman). Finally he appears as the mythical founder of the science of architecture (vastuvidya).
Visvakarman Puja has been declared by the Government of India on a particular day, i.e., 17th of September, considering the secular tone of the celebration. According to Hindu tradition, it is observed on Sravana Light half 5 and still most of the Lohars (Iron-smith) and Barhai (Carpenters, etc., celebrate it is their houses. On mass scale, smaller industrial units celebrate it on 17th of September.