When painting blue plastic models for a non-Ultramarine paint

MRPF020F MRP Aqua Figure Paint Line - Ultramarine Blue 17ml

1:12 Scale Miniature Rocker Chair in Ultramarine Blue or White

I think my Contrast painted Ultramarines look really good, what

When painting blue plastic models for a non-Ultramarine paint

What paints and techiques should I use to get such a vibrant Hive Fleet Hydra colouring? I want to start painting Tyranids and could use some advice : r/Tyranids

Paint coming off. : r/Warhammer

Is it always best to base metallics with gloss black or are there other options? : r/Warhammer40k

Vallejo Hobby Paint Spray - Ultramarine Blue

Color Temperature within Painting – Opus Art Supplies