Do such things exist? Any recommendations ?

How inconspicuous do you think they'll be when they're covered in mud?

You can get inflatable ones….

Mtn or town?

Mtb

Try the muckynutz ones

Well you DON'T want TJ Ltd's T.Cone Mk1 model.

onlookers don't think an MTB is cooler without mudguards – they think we look quite stupid with or without. just get some that work

The Bender Fender does some good, keeps a little more crap out of your eyes, but it's no alternative for a mudguard really.

If you're going to do mudguards, do it right or don't do it at all, is my advice- ineffectual mudguards like a downtube-mounted crudcatcher look pretty much exactly as bad as a fork-mounted one like a Shockboard, while not actually doing much of any use.