This is 3D printing part science part art. Move them how you want them, when you get them how you want them save a factory file so you can get back to that sport if you screw it up or need to reprint them in a week. File > save factory file as > all parts for mask set up V1
This way if you find you need to change and it does not work you can open that file and you changes are back how you want it.
Control-Z also undoes changes up to a point.. get in the habit of saving factory files as you will spend a lot of time setting up a job and when you want to do it again you will not want to waste that time.
Good luck!
Another possibility is to rotate some of them 90 degrees on the Z axis. The center-and-arrange function may figure out how to get them all within the confines of the bed.
Netfabb has a great 2D build plate packer for situations like this. With it, I've been able to pack more parts on my build plate than imaginable. If you don't have access to it and want to pack a lot of these clips, send me a PM and I could help pack them with it.
It's pretty simple to crowd the plate without having problems.
You paid a lot of money for the freedom of doing stuff other software doesn't easily do.
Simply hold-down the command-key and drag a part close to another part and repeat. They don't need a a lot of space between them.
Example below (it wouldn't matter if they were curved or not)...
Attachments
3D Print Parts
https://www.thingiverse.com/Still_Breathing/designs