This is such a fun but easy Birthday surprise! It’s super quick to set up and very inexpensive. My daughter was so surprised and excited when she opened her door the morning of her birthday and balloons rained down on her. 
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Supplies used:
Crepe paper streamers
Clear packaging Tape
Balloons
Balloon pump (optional)
After my daughter went to bed the night before her birthday, I set this up by taking strips of crepe paper streamers and taped them across the top half of the door frame in cross crossed patterns. I found clear packaging tape worked best (scotch tape broke when putting the balloons in place). I only taped to the door frame and not the wall (the tape could pull paint off the wall, but removed cleanly from the door frame). I then blew up a bunch of balloons with my Bunch O Balloons Portable Party Balloon Electric Air Pump. This pump is awesome for blowing up 40 of the Zuru brand balloons in 40 seconds with air or helium. It also includes an attachment for just blowing up any balloon with air quickly (and without having to blow with your mouth).
Once my balloons were blown up I just wedged them between the streamers and the door. They stayed in place all night and when my daughter opened the door she was so surprised by the balloons falling on her. It only took a couple minutes to set up, was made entirely with supplies I had on hand and was such a fun way to start the day!
MagpieTayleetot is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. All items used in this tutorial were purchased by me and I did not receive anything in exchange for this post.