The base card needs to be at least 100 lb weight paper. You don’t see much of it. It is mainly there for support and structure for the Birthday Flip card. Patterns have no point. But the overlays and embellishments can be any paper including patterns as long as the pen shows up.
Cutting the Card
First re-crease all the fold lines. Work the card a couple of times to make sure it flips correctly.
Next glue the birthday cake and ballons on the overlays for the flippers. Then glue the birthday cake overlay to the flipper on the back side. Now you can flip the flipper and attach the balloons flipper to the other side. Finally glue the other overlays to the base card. I thought that the card needed more so I put a little washi tape on each side.
Your Birthday Flip card is done. Enjoy!