What printer around 600€

[curious aardvark]

depends entirely on how much flex you want.

My current stock would rank like this:

super wobbly: ninjaflex and filaflex (rubber) virtually indestructible
not quite so wobbly: flexismart (rubber) - nowhere near as strong as the other filaments
bendy and very flexible when thin but can be made firm with the right settings - virtually indestructible: polyflex (pla)
bendy but stiff: cheap flexible pla - No idea what make it is. But the really cheap flexible pla is pretty stiff in comparison to polyflex.

They will all stick to pretty much anything and don't need heated bed.

[oxidized]

depends entirely on how much flex you want.

My current stock would rank like this:

super wobbly: ninjaflex and filaflex (rubber) virtually indestructible
not quite so wobbly: flexismart (rubber) - nowhere near as strong as the other filaments
bendy and very flexible when thin but can be made firm with the right settings - virtually indestructible: polyflex (pla)
bendy but stiff: cheap flexible pla - No idea what make it is. But the really cheap flexible pla is pretty stiff in comparison to polyflex.

They will all stick to pretty much anything and don't need heated bed.

Let's say i want to print a flexible cover for my smartphone that resembles the one you buy made out of silicone rubber, which one should be the closest?