Here is a set of 3 mask adapters. They are designed for DeltaPlus masks.

They allow :

• to close one of the two inlets
• to adapt the mask for a standard CPAP hose (22mm)
• to remove the charcoal filter and only keep the FFP3 filter

You can combine as needed...

It fits perfectly, no air leak.

Used here : https://www.thingiverse.com/thing:4303543 to build an experimental Powered Air Purifying Respirator (PAPR)

Prusa

i3 MK2S

200

100