Any home made tricks to fill up a baloon that floats?
There are some options, not all easily available or safe: Helium is the most used and it most certainly makes them float, being safe at the safe time. However, it's not an home-made trick. Methane is more easily available (in many cities, methane is piped into homes for domestic heating and cooking purposes) but it's very unsafe for such an use, as it could explode. Hot air is also used (think of hot-air balloons) but I wouldn't know how to make it last for a long time as the air would cool down to room temperature very quickly. Lastly, there's hydrogen which could also be produced with some reagents available at home, but it's as dangerous as methane.