Face shield, Prusa style (compatible) – emergency PPE

Various efforts are underway in the 3D printing community to supply emergency Personal Protection equipment to health professionals. Many designs are makeshift, none are exactly approved for medical use, not least because fused deposition manufacturing is hardly the approach of choice for making stuff that might need to be decontaminated.

The nearest I’ve found to an “approved” design for a medical protective face shield, to be worn with an additional filter mask and maybe goggles, is something that Prusa (3D printer maker) developed and made freely available, and which was approved for emergency use by the Czech medical authorities.

Find the Prusa designs (3 major iterations) here:

https://www.prusaprinters.org/prints/25857-prusa-face-shield

Prusa’s website has extensive instructions on all aspects of their face shield design, including how to assemble the face shields, a cutting guide for the transparent shield part itself (which I will refer to as the blade, below), various iterations of the headband and the bottom piece. It invites community remixes, carries a bunch of gcodes for swift printing of the various parts, including some clever stacked prints for overnight batch manufacturing.

They also have remixes suitable for the 150mm x 150mm bed printers popular with schools etc – the “RC3” design is considered the best at time of writing, but won’t fit on a 150mm bed.

The RC1 design is printed pre-tensioned and takes much less bed space, and fits easily within 150x150mm, and prints a lot quicker than later revisions, but it’s weaker and less comfortable. All designs can be split in two and joined with some kind of reinforcement and cynoacrylate glue. (Note that CA glue will degrade/separate if steamed or immersed in hot liquids for long.) I also prefer the RC1 strap toggle design, which should be perfectly strong enough unless there’s something wrong with your filament.

Looking at their RC3 headband design, I decided that the deep corners created by the blade mount extensions (to push the blade out a little flatter and wider) are a dirt trap, and also needlessly complicate the tool path, so I’ve created a compatible design from scratch using TinkerCAD, with what I consider to be the obvious redesign to get the same blade distance and curve but less material and no dirt trap. TinkerCAD is more limited than whatever Prusa’s designers have used, so my curves are not as smooth, and I’ve not added the top chamfer on the strappy sections. A bottom chamfer on the head-side of the forehead band would be more to the point, but in the interest of bed adhesion and simplicity, I’ve not added this either. Note that my version does NOT fit their top cover. I have a version with lugs that an acetate top cover could slot onto, I will upload an outline for that in due course. I’m not entirely happy with the lugs, though, this is subject to change.

To be honest, a quick and simple top cover mod would be to use gaffa tape (duct tape) on the outside, which could also cover the small gaps left by the blade holes around the mounting pegs.

Prusa’s RC3 design dropped the hexagonal holes in the forehead band, as they found that sweat was a non-issue on a 20mm wide band and the holes could have sharp edges if printed fast. They thickened the bands, too. The print time went up for each revision – with my own extremely conservative print speeds, at 0.24mm layer height on a 0.4mm nozzle, I get just under 2 hours for RC1, and it comes out at 30 grams exactly, using 10m of 1.75mm filament. RC2 unwinds the design for a more comfortable fit on the head (and will no longer print on 150mm beds). With the same print settings, it goes up to a 3hr 12min print, using 49g of material, 16.5m of 1.75mm filament. RC3 thickens the bands and dispenses with the holes, going up to a 3hr 17min print using 53g (17.7m) of filament.

My redesign puts everything in the same place as RC3, selectively slims the bands in the middle where it doesn’t significantly compromise strength, and does away with the arm-extension complication. With the same print settings, I’m getting 2hr 20min print time, using 37g (12.4m) of material, or 2hr 20min and 38g (12.7m) of material for the version that I’ve added inner lugs to for mounting a top shield.

This is a work in progress, so expect further revisions, but I’m inclined to stick to the Prusa blade design and hole layout, because it’s good to standardise these things.

Note that this was intended by Prusa to be printed in PETG, which is more temperature-tolerant than PLA. However, many health authorities/personnel are treating these as single-use, having no time for cleaning and sterilising them, in which case PLA is a better option for the environment because it will eventually biodegrade.

Accordingly, I have added a material code to the side of this design – raised, rather than sunken, as again I feel that the sunken “PRUSA” logo was a needless dirt trap.

In the first instance, to get this up and shared quickly, I have only a “PLA” badged design, as, being British, I have stuck a “heart NHS” legend on the other side. I will upload a PETG version and one without the NHS legend ASAP. Also other refinements.

This is a work in progress – I will add files and information here as and when I can.

Whether or not you like or print my designs, if you have a 3d printer and there is a shortage of PPE among health authorities in your area, find out what they need and how best to deliver it (local clearinghouses) and get printing… there are loads of designs out there, and we can help.

Please read the section on printing, because I ran into issues with Cura, and please also read the Prusa web site linked for information about the blade pattern, how to make and distribute these things, the bottom pieces required, etc.