3D printing rack ears/rack mounts

I need some custom rack ears for a standard 19" rack, and I would like to use a printing service to print them for me.Unfortunately, I'm a complete noob to 3D printing (I can use Fusion 360 tho). I am quickly realizing that there are so many parameters to 3D printing!How can I ensure the printed rack ears can support the loads? The heaviest devices weigh 3kg/6.5lbs.Even though I'm not the first (there are some rack ears on Thingiverse), there isn't so much technical information to work with, and I'm lost as to how to answer this question. Where do I even start? For starters, I have no idea or feeling of how strong 3D printed items are. Is SLA the right methodology? How can I tell which filament I should use? Which infill pattern? Which infill density?Thanks so much!