Have you ever been stuck without a pump and had to inflate a queen-sized air mattress using only your lungs? I have, and I wouldn’t recommend it; I nearly passed out several times. A pump is the obvious solution, but why buy a pump when you can use another tool you already have?
Not all Shop-vacs and knock-offs have a blower, but if you have one that does, attach Shop-Vac’s inflator nozzle and you can blow up beach balls, mattresses, pool toys, or any other low-pressure inflatable product. The nozzle works with both 1-1/4″ and 2-1/2″ diameter hoses.
You can find the inflator nozzle starting around $10.