Still with balloons (because who doesn’t love a balloon, right?) how about an upwards reveal thanks to helium balloons?
Order helium balloons in your chosen gender colour and seal tightly into a box decorated with ???
This can be a great way to involve existing children in the celebration. You might not want them involved in putting the balloons into the box, if you’re worried they’ll reveal the colour, but you could certainly give them the important job of opening the box at the right moment.
This idea also works well alongside the gender confetti balloon pop, especially if you get the guests to count down to the big moment, 3-2-1 style!