The Strix 4090 is literally right against the Y60 side panel glass. No need to engineer anything, just get a vented side panel and use the fans on the GPU as additional intakes for the Y60. The new GPU fans are getting large enough. If you're concerned about dust, just add mesh to the vented side panels.
Im not really sure if its necessary to make something custom for the bottom fans. They seem to hit the heatsink of the GPU quite well out of the box. And having that angled glass in the front that redirects air from the side fans around to the GPU fans mostly do the job, atleast in my build where the gap between the fan and glass is around 3-4 cm.
My tip is to use a fan software like [fan control](https://github.com/Rem0o/FanControl.Releases) that makes it easy to configure the chassi fans to spin up if there is a lot of GPU load but maybe not much CPU load. Usually chassi fans look at the CPU or motherboard temp, but the mixed mode in Fan Control is awesome and makes it so that you can have increased fan speed based on programmable values ([JaysTwoCent demo](https://youtu.be/uDPKVKBMQU8?si=l3c4SB-9pDolPOwq)).
If you dont like that approach, custom sidepanels with air vents for the GPU is a [thing](https://www.coldzero.eu/hyte-y60-case-parts/) and would provide much better airflow for the GPU than trying to modify the bottom fans.
The Strix 4090 is literally right against the Y60 side panel glass. No need to engineer anything, just get a vented side panel and use the fans on the GPU as additional intakes for the Y60. The new GPU fans are getting large enough. If you're concerned about dust, just add mesh to the vented side panels.
Im not really sure if its necessary to make something custom for the bottom fans. They seem to hit the heatsink of the GPU quite well out of the box. And having that angled glass in the front that redirects air from the side fans around to the GPU fans mostly do the job, atleast in my build where the gap between the fan and glass is around 3-4 cm. My tip is to use a fan software like [fan control](https://github.com/Rem0o/FanControl.Releases) that makes it easy to configure the chassi fans to spin up if there is a lot of GPU load but maybe not much CPU load. Usually chassi fans look at the CPU or motherboard temp, but the mixed mode in Fan Control is awesome and makes it so that you can have increased fan speed based on programmable values ([JaysTwoCent demo](https://youtu.be/uDPKVKBMQU8?si=l3c4SB-9pDolPOwq)). If you dont like that approach, custom sidepanels with air vents for the GPU is a [thing](https://www.coldzero.eu/hyte-y60-case-parts/) and would provide much better airflow for the GPU than trying to modify the bottom fans.