I am not related to Cathay Photo, but I think this product might interest members here:
Quote from the website:
Lumiquest Promax 80-20
$26.00
The ProMax 80-20 enlarges and redirects 20% of the light at a 90° angle from the flash and allows 80% of the light to pass on, to be redirected by another surface -- most likely a ceiling.
Application: This device illuminates the scene with light bouncing off the ceiling while providing "fill" light off the bounce device itself. For use in situations where an 8-9 ft. ceiling is available.
Light Loss: Variable depending on ceiling height.
Dimensions: Folds flat to 4 1/2" x 7 1/4".
If you want 100% reflection you can just cover the opening with a reflective card.
Regards,
Roy

Quote from the website:
Lumiquest Promax 80-20
$26.00
The ProMax 80-20 enlarges and redirects 20% of the light at a 90° angle from the flash and allows 80% of the light to pass on, to be redirected by another surface -- most likely a ceiling.
Application: This device illuminates the scene with light bouncing off the ceiling while providing "fill" light off the bounce device itself. For use in situations where an 8-9 ft. ceiling is available.
Light Loss: Variable depending on ceiling height.
Dimensions: Folds flat to 4 1/2" x 7 1/4".
If you want 100% reflection you can just cover the opening with a reflective card.
Regards,
Roy