This snowflake fidget spinner is designed for a 608 bearing (grease removed) - 22mm by 7mm, and 10mm ball bearings. Degrease by removing the retaining rings and washing it in acetone, or similar, then drying and replacing the rings. There are plenty of guides out there for this.

You should be able to push the bearing into the centre ring by leaning into it on a table. Once you get the bearing in a little turn it over to push the spinner down the rest of the way onto the bearing (it's just easier on the hands). The ball bearings can be tapped in with a hammer (tap it, don't whack it), or pressed in with a vice. I intended to push them through until there was 1.5mm sticking out both sides of the spinner but ended up pushing it to be flush on one side so that it could spin on the cap on a flat surface. The balance is fine either way.

Tevo Tarantula

No

I used a brim, not a raft, although either should be fine, but if your setup is good enough print it without anything as it will be less to tidy after.

A small screwdriver can be used if you get out any stringing inside the design. I used PLA, slightly too warm, and had to clean out some tags and strings.

Use a Dremel sanding cylinder or grinding stone if you need to tidy up the bearing/ball rings.