So I remember taking apart office clips when I was younger. I remember there was this design of 2 piece clip with a center spring. i wanted to recreate it and this is what I ended up with.

I added 2 size Springs, 3mm and 4mm thickness for more or less tension.

This is a work in progress, but pretty much it is almost perfect.

To put it together simply print 2 units of the clip arms. then 1 unit of spring.
insert the spring to 1 of the clip arms first, then thread the other side of the spring through the under side of the clip arm, there is a lock for the spring to attach to so that it stays in place.

It's somewhat like a puzzle also when putting it together. Have some fun assembling.