A good surprise for your girlfriend. When she opens the door, rose leaves will fall for her :)
You can prepare this surprise in 30 minutes, if you have the materials.
Here is the list of materials.
1) Rose leaves
2) Laths (for kites, see the picture)
5 meters (5 times 1 m parts) will be enough, if you want to prepare this mechanism for the size of standard doors.
3) Simple small saw
4) Hot glue gun and glues
5) Craft knife
6) Cardboards (size depends on you I used 2 plates in the dimensions of [1m wide x 40cm long] )
Step 1: Preparing the Base (rose Holder)
Cut the cardboard in the dimensions that you want. I used 1 m wide 40 cm long. Then attach laths with hot glue into cardboard. Later, cut laths into small peaces for triangular support that can be seen in the figures. 3 triangular supports will be enough. Height of the supports are approximately in between 20 cm - 30 cm. Sizes are up to you. As a final step for the base glue the system into upper end of the door.
Step 2: Preparing the Cover (rose Sweeper)
As an upper part we will prepare cover. This cover will make the roses fall when she enters the room. As in the previous step, cut the cardboard in the same dimensions of base and attach triangular supports at this time support size can be smaller then base.
To put roses in between these plates there must be a gap. And also there must be a sweeper apparatus. We will cut this sweeper apparatus from cardboard and its height must be equal to the height of the gap. See the picture for the definitions of sweeper and clearance.
Glue the sweeper into cover
Then glue the cover into wall on top your door. Be careful about sizing. sweeper must touch into base to sweep roses.
Step 3: Deploy Roses Into Gap
Gently put roses in between plates (base-cover)
Be careful when you are going out. You may make the roses fall :)
If you want to go out put the roses very near to sweeper and prepare this system longer than 40 cm.
Good luck. Don't forget to watch the video :D