If you want a children's apron that is supremely waterproof, lightweight and easy to clean, then make one from used umbrellas.
Seriously, who dreams up these ideas? I've got at least 3 broken or wonky brollies taking up space in my garage, not once have I thought, "I know! I'll recycle dodgy umbrellas and turn their material into kids waterproof pinnies!"
The official blurb on the site says:
No-mal provides protective clothing for little painters, builders, creative eaters and other young masters of their trade. Each apron is a one of a kind, made from recycled umbrella-covers and manufactured in sheltered workshops.
Minor sings of wear and use may appear and are considered part of the product. The apron can be washed 30°C.
Genius and quirky as they are, I'm not sure I'd pay 37 Euro for a No-Mal kids brolly apron.
If you were suitably talented in the sewing and garment making department perhaps you could make your own, or something similar; you can have my umbrella material as sewing is NOT my strong point.
Forget the eternal 'how many people does it take to change a lightbulb?' question and ask yourself instead 'how many brollies does it take to make an apron?!'