What is Reddit's opinion of StarTech.com 1U Server Rack Shelf - Universal Rack Mount Cantilever Shelf for 19" Network Equipment Rack & Cabinet - Heavy Duty Steel – Weight Capacity 33lb/15kg - 7" Deep Tray, Black (CABSHELF1U)?

From 3.5 billion Reddit comments

I'd probably suggest just using a rack shelf. You can put a Velcro sticky pad on the shelf and the bottom of the pi case so that it stays fastened down but can still be moved if required. You'll obviously have lots of spare space on the self which you can use for cold spares, more pis etc.

Something like this. There are lots of different types and brands though. Get whatever depth you think you'll need.

google 1U rack shelf

for example: https://www.amazon.com/StarTech-com-Server-Rack-Shelf-CABSHELF1U/dp/B005G2JFEO

Is this the shelf you picked up?

EDIT: Do you mind sharing a photo of your setup?

https://www.amazon.com/StarTech-com-Server-Rack-Shelf-CABSHELF1U/dp/B005G2JFEO/ref=pd_lpo_147_t_1/133-2537245-6610154?_encoding=UTF8&pd_rd_i=B005G2JFEO&pd_rd_r=eda20174-61cf-4647-9654-500a2ded1e06&pd_rd_w=n5QBK&pd_rd_wg=ndmFR&pf_rd_p=a0d6e967-6561-454c-84f8-2ce2c92b79a6&pf_rd_r=80KRB8R77HPV69RDSMBP&psc=1&refRID=80KRB8R77HPV69RDSMBP

That's the rack mount kit, not the actual DAC. I use this.