Description

This is a remix of the DtM 3.1 NIH approved face shield with a print-in-place hinge to allow the visor to flip open. The shield profile is also modified to wrap around the sides more (similar to the DtM 4.0 injection mold version shape); as a result, there are also tabs added on each side to help secure the shield material. I have also included a non-hinged version with the same profile and side tabs.

Revisions:
12/17/20: Mk2 - simplified hinge area to only have 2 detents (middle positions drooped with use anyway); decreased hinge gap clearance from ~0.5 to 0.3 mm to reduce loosening over time. Adjust step file as below to further tighten or prevent fusing as necessary. .

Materials

The frame can be printed with any PLA or PETG filament
Any transparent sheet can be used for the shield itself - mounting holes are for a standard US 3-hole punch as with the source design, and the side tabs accomodate up to 11.5" width (or slightly oversized if the corners are rounded). Heavy (8 mil+) transparent report covers work quite well. Due to the mounting system, the thinner, overhead projector transparency sheets are more likely to rip, and do not hold shape as well. The bottom curved reinforcement shown in the photo is optional; the original Prusa RC3 reinforcement available here works well.
Foam insulation tape can be used to cushion the headband if desired; a towel or gauze bandage can also be wrapped around the frame for the same purpose.

Printing Parameters

Use layer height of 0.2-0.28 mm - smaller layer height is overkill and just dramatically slows the print; I have not tried larger heights but it might cause the hinge portion to fuse.
Extrusion width should be increased to 0.6 mm (150% on a 0.4 mm nozzle) - this will help speed the print, and reduce the likelihood of the hood portion delaminating/failing.
Use 3 perimeters for strength; infill can be 0-25% (basically only cosmetic and helps to make the "roof" of the elastic hook section to not cave in if your printer does not bridge well).
As long as you use 3 perimeters, top and bottom layers can actually be set to 0 and it will retain its structure and save a few minutes of print time, but a few areas will have a "wireframe" appearance. Set to 2 layers to have a better cosmetic result.
With these parameters and some basic velocity tuning, I got a print time of just under 2 hours with PLA on my (not particularly well calibrated) Ender 3 for the hinged version, and 1:45 for the non-hinged version; PETG print times are about 30 min slower (my printer is finicky with PETG).

Creality

Ender 3

No

No

0.24

0-25%

See printing directions

With PETG, warping sometimes causes the front frame to pop up from the bed, which results mainly in distortion of the hood (still usable, just a little weird looking). Interestingly, I have never actually had the print fail due to detachment as there are many other anchor points (rear hooks, around the hinge).
The other common failure is the outer "cover" of the pivot joint getting knocked over before it attaches to the "axle," which can cause the joint to fuse, or the whole print to fail in that area.
For both problems. adding "mouse ears" (1 layer thick squares/circles) in the slicer in the areas where you have this problem works very well; example areas are shown in one of the images. You can actually align the perimeters such that they peel off afterwards without even needing tools. To remove the hinge area supports, I just use flush cutters to cut off the entire "rectangular" support area on the bottom of the hinge (when viewed from the side) that the mouse ears are attached to, leaving only the circular profile.

The profile has been reshaped to allow much faster printing than the original model, with only 2 horizontal layer thickness. If you use 0.6 mm extrusion width, there should be no issue, however if you find that print times are very slow, or you are getting a lot of blobs/irregular areas, it could be that the slicer is trying to gap fill. If so, add a modifier block covering the entire hood (or height modifier >16 mm), where perimeters are set to 1, top and bottom to 0, and set gap fill velocity to 0 to disable (see screenshot for Prusa Slicer). Also, try decreasing minimum layer time if your cooling can support it without distortion of the print.

I have intentionally left a lot of tolerance to allow for fast printing and printing on printers that are not very well calibrated. If the hinge is stuck, use pliers to stabilize the outer, circular portion relative to the main frame while slowly rotating the hood section upwards; this should break it free without shearing the support "axle." Repeat on the other side (there should be enough flex to do this one side at a time).
If you find that the hinge is too loose (maybe if your printer is extremely well tuned), I have included the STEP files; the easiest way to tighten the clearance would be to extrude the circular profile surface of the hinge area by 0.1-0.2 mm in one/both directions.