It is quite an arsenal: some 1,500 multicolored balloons, packed snugly into a supply belt below the rainbow suspenders of Ed Braunstein (nom de guerre Chester the Balloon Jester). They are not blown up yet, of course, but they will be. A crowd of children has gathered near Braunstein in the Public Garden, where he plies his elastic trade for tips three or four times a week in the warmer months. The making of balloon figures has a singular sound, one that conjures childhood and its simple satisfactions: the inflating, then the squeezing and twisting into shapes, and the glee that follows. “Butterfly hat! Yeah!” a satisfied customer says upon receiving her pink and purple creation. Braunstein, who lives in Brookline and gives his age as “mid-50s,” has been at this about a decade. A former software engineer, he taught himself the craft from library books and videos. He is rarely stumped, he says, but he does politely turn down frequent requests to make Justin Bieber. He typically burns through 500 to 600 balloons daily. Braunstein has two school-age children but rarely makes balloon figures at home. His wife imposed a ban after too many pops.