Ideas for gender reveal

We had our 20w scan and results are in a sealed envelope. We want to do a small gender reveal with grandparents only at their place. The trouble is we dont know anyone nearby who can fill a confetti in balloons based on our envelope results. Neither do the nearby bakeries do gender reveal cakes. Any ideas how to pull off a surprise for all of us? I seriously dont want to see the envelope beforehand and do the arrangements.