Folding Foggles - IFR View-Limiting Glasses (Snap Hinge, No Hardware)

Glasses-style IFR view-limiting device ("foggles") for instrument training and proficiency flying. It wears like normal glasses instead of a hood, blocks the view outside while leaving the whole instrument panel visible, and the temples fold flat so it fits in a flight bag pocket.

Features

• Folding snap-on hinges, no hardware. Each shield end has a 4 mm vertical post with a collar. Each temple ends in a 9 mm C-ring that snaps onto the post and pivots on it. No pins, screws or glue.

• Positive open stop. A tooth beside the post stops the temple at the open position with 3° of toe-in for grip. The temples fold inward to about 100°.

• Cannot pop off in use. The pull-off direction on your head is the closed side of the C-ring.

• Real nose bridge. Nose notch plus two angled pads with standard eyeglass pad geometry (17 mm apart).

• Ear hooks. Temples bend down behind the ears.

• Prints without supports. The post is a plain cylinder growing upward, the bracket meets the shield at more than 45°, and the ring stands on its edge. There are no holes and no bridges.

• Parametric. OpenSCAD source included so you can adjust the fit to your head.

Files

• foggles_hinge_print_front.stl: the shield. Print as oriented (upside down, brow flange on the bed).

• foggles_hinge_print_temples.stl: left and right temples, two separate bodies lying flat.

• foggles.scad: parametric source. Set joint = "hinge" for this version.

Print settings

• Material: PETG (dry the spool first, wet PETG strings badly on the thin walls)

• Nozzle: 0.4 mm, layer height 0.16 mm

• Walls: 3, inner before outer

• Supports: none

• Brim: outer only, 4 mm wide, with a 0.3 mm gap so it peels off cleanly

• Nozzle temperature 225 °C, part cooling fan 60 to 80 %

• Retraction 3 mm at 40 mm/s with a 1.5 mm wipe and 0.3 mm Z-hop to control stringing

• Print time: about 2.5 hours for both plates on my printer

Let the bed cool completely and flex the plate to release the parts. Do not pry at the shield ends or temple tips, a 2.4 mm PETG wall can snap across its layers if you lever it.

Assembly

1. Hold a temple in the open position with its ring next to the post, at the height between the bracket and the collar.

2. Push the temple outward until the ring clicks over the post. The opening of the C faces your head.

3. Repeat for the other side. Fold and unfold a few times to seat the hinge.

4. To remove a temple, pull it inward off the post.

If the snap is too stiff, raise ring_gap from 3.6 to 3.8 in the SCAD file. If it is loose, lower it to 3.4. Only the temples need reprinting.

Fit tuning (top section of foggles.scad)

• hinge_half_width (77): increase if the temples squeeze too hard, decrease if they barely touch.

• toe_in (3): side grip. 0 means the temples go straight back.

• ear_distance (88): where the ear hook starts. This is the number most likely to need a change.

• center_bottom (-4): how far down the shield blocks. Lower it if you can see the windshield, raise it if the top instruments are hidden.

• wall (2.4): shield wall thickness.

Field of view

Ray-cast from the modeled eye position: straight ahead is blocked from about 11° below the horizon upward, everything lower is clear so the full panel is visible, and the wrap-around sides block the peripheral view down to about 25° below the horizon.

Notes

• Use only with a qualified safety pilot or instructor on board, as required for simulated instrument flight.

• The nose pads are hard PETG. Stick-on silicone eyeglass pads make them more comfortable.

• The modeled head uses average dimensions, so expect to tune the fit.

• Designed in OpenSCAD with AI assistance. The cover image is a render of the assembled model.

• Inspired by the Thingiverse "IFR Simulation Hood" (thing:5859191). This is a new design, not a remix.