Very fun short! The part where he is putting together the balloon was really cool with the shadows over flat colors.
I think some more care into the sound effects would help this cartoon immensely (sometimes repetitive or clunky SFX can be distracting & affect the viewer's immersion). I also think this cartoon could benefit with either colored lines or lineless backgrounds to make the characters & objects on the foreground pop out better (saying this as someone who LOVES black lined characters, it helps a lot! Try it out & see if you like it!)