replacement pedal for kids pedal cars such as Big Wheels

My son inherited an old pedal car that had the usual missing pedals. Most pedal shafts are 3/8" or 5/16" shaft which mine was the 3/8". Turns out most Big Wheels today use a 3/8" shaft so this may be useful for those with Big Wheels.

Notice the peal has rounded edges but the patter still provides a decent grip for little feet. You will need a "Push washer" that is placed in the middle open slot to hold the pedal on the shaft. I was able to buy one at my local hardware store by robbing the inner washer from a push on cap that looks like this one sold here http://www.amazon.com//dp/B000UM2BTQ ... the goal is to buy a push washer like the example picture in this listing or like the one sold here http://www.amazon.com/dp/B007TQWA74/

Hope y'all find this handy!

UPDATE: by request I uploaded the FreeCAD design file so other can edit or make their own variation in less time ;)