This respirator is based on research (1, 2, 3) showing that cotton can be a relatively effective filter for stopping B Atrophaeus, bacteria that is roughly 1 nm in length (Source). A double-layered, thick-woven tea towel had similar filtration capacity as a standard surgical mask (96%), and even a double-layered cotton T-shirt had 70% capacity.

It currently uses Target-brand double layer makeup pads as a filter. However, these filters can be swapped out with cut-up N95 masks or other filters.

It should be printed out of TPU, a commonly available filament. Assembly instructions and further details can be found here:

http://jordanpelovitz.com/elevons-covid-19-respirator/

Note: Filter is dual-sided cotton makeup rounds. The ones I designed for are from Target are 54mm/2″ in diameter.

This model passed a fit test at a major metro hospital in Boston, MA.