Double Shell Packaging With Vacuum Formed Foam Shells

What issues should be noted for double bubble shell packaging?
Double bubble shell packaging refers to a packaging form in which two bubble shells are used to package paper cards and products together. Its characteristic is that it requires a high-frequency machine to seal the edges of the double bubble shell, which is inefficient and has high packaging costs. However, the edges are neat and beautiful, and the product appearance is high-end.
The issues that should be noted are:
1. The blister can only be made of PVC and PETG film, otherwise it cannot be heat sealed or the heat sealing effect is poor;
2.The quality of the edge of the double bubble shell is determined by the quality of the high-frequency mold.