Stroller wheel hub cap
A lost hub cap lets grit into a stroller wheel bearing and exposes a sharp axle end, and manufacturers seldom sell the cap alone. The cap is a 40 mm diameter dome 12 mm tall with a 2 mm wall, an inner ring of three snap tabs that grip the 30 mm hub lip, and a small pry notch on the rim. A fillet on the tabs lets them flex without cracking. Print it dome-up with a brim in PETG for a snap that survives many removals.
Measure the hub lip and cap diameter and SpeakCAD produces a cap for that exact wheel, in whatever count you need. If the snap is too loose, ask for the tabs to be 0.2 mm taller and regenerate. Trying it is free and runs in your browser with nothing to install.
Create a stroller wheel hub cap 40 mm outer diameter and 12 mm tall with a 2 mm wall and domed top, three internal snap tabs 1 mm tall and 6 mm wide on a 30.2 mm diameter, a 3 x 2 mm pry notch, and 0.5 mm tab fillets.