Remixed from https://www.printables.com/model/174961-conic-section-models.

I've added holes to glue some little magnets to allow the model to stay toghether and to easily form the cone which now stay in place.

I use this one from amazon : https://www.amazon.it/gp/product/B07T13H3R5/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

but any neodimium round magnets 5mm * 1mm thick will work.

Glue in place with super glue. Just before glue it, verify if the hole is right dimension and the magnets does not tick out the profile of the hole, in case adapt the hole with a cutter.