Maybe you and I have different medical masks in mind? I was talking about masks like this:

https://cdn.shopify.com/s/files/1/0080/6830/0851/products/6_...

https://www.123rf.com/photo_138981777_stock-vector-person-we...

https://phonetub.com/products/100-disposable-face-surgical-m...

The main problem with blue masks and home made is that they tend to get wet from breath and their effectiveness go down the drain.