Let's talk about PC cases with glass panels, in front, they are pretty but useless, there's no airflow at all.

For example my new case, a 'Rise Mode Glass 06x', the original gap for airflow on the front is only 2.8mm, this is for 3 fans, so those fans are just decorative.

For that, I designed some simple spacers, to enlarge the gap to 17,8mm, they will work not just for this Rise Mode model, there are a lot of PC cases with this problem.

In my scenario (3 frontal fans, 1 in the back, and 2 at the top), it reduced the CPU temp by 10° Celsius.

You only gonna need some M3 screws that match the ones in your PC case, use some glue to fix the printed heads.

I've tested the airflow with smoke, and it worked, but I recommend putting some kind of dust cover on the front panel.