Some thoughts on blend door design
The use of foam is related to weight and price. Foam is much less expensive and lighter than the older approach of using felt. The foam (like the older felt) provides a few functions.
1) It seals the door way when its closed
2) It helps with NVH (reducing door noise as it opens and closes)
3) contributes to the weight and cost of the vehicle
4) The foam insulates, providing temperature transfer through the door
Those holes you see in the blend door frame material are there to allow the adhesive backing on the foam to stick together one side to the other, causing a much better bond than adhering to a solid metal frame. Think of the blend door metal component as a frame not a door. The frame is made of metal because it expands and contracts to temperature much less than the plastic the housing is made out of.
Anything related to the blend door is subject to the extremes of heat, cold, and moisture from both external air as well as the HVAC coils.
To work well the blend door must seal when close, and the material used must have high resistance to airflow through the material and low resistance to airflow over the material.
Now one can understand the reasoning behind the design and can make adequate determination as to what replacement materials would be adequate for repair.
Adhesion:
Consideration needs to be given to using an adhesive and material that will last the life of the vehicle. I suggest considering dryer felt adhesive as it is designed to hold up to the extremes of hot and cold. If one lives in climates where the temperatures are extremely cold, then a silicon adhesive might be the better choice. Make sure the adhesive will perform at the lowest temperature as well as radiator temperature (about 200 F or 100 C). Of course the best adhesion is a mechanical attachment, just remember there are laws in play related to the physical operation of the door VS weight of the door assembly.
Material:
We know that foam is not the best choice to achieve the purpose of the blend door. Therefore it would be better to choose a thin felt which wool felt being the number one choice. Wool felt will resist moisture and perform well as a seal in both cold and hot conditions.
The best material would be a rubber seal that is affixed to the metal blend door by fasteners, the rubber seal would fit around the outer edge of the blend door. With the seal in place thin felting could be shaped and glued to the remaining door frame, thereby resisting flow through, temperature transfer through and allowing flow past the material.