It never came across my mind that putting a balloon inside another was even possible until I saw this photo of a party that I published last month. It was a Mickey Mouse Party by Olivia of Invento Festa. Olivia uses a clear helium quality balloons.
What I found – I went to youtube, my favorite channel for all the “how to do stuff”. Many of them were using the air pump which I didn’t have at home, so I kept searching and came across this video below that didn’t require a pump, finally… he used only two plain balloons! So here is the video of “how to put a balloon inside a balloon’ by MrErikZilla via Youtube.com.