Makita DUB185Z DUB186Z (Affiliate link) Adapters for inflatable things with different nozzle widths.
Pay attention to the picture and check your blower, there seems to be a similar blower from Makita with a different fitting.
The adapter overall is 80mm long, the upper cone part is 20mm long.
I recommend to print it with TPU, but PLA and so on will also work.
Print Profil Build Plate selection: