The Retro Renovation blog shared an Etsy listing for a few new old-stock Honeywell Tap-Light switches. I'm pretty sure that this is what we installed in my stairwell! One switch that is listed has a clown face that is similar to the one on my switch, and there is a pattern shown on the package that looks like the blue pattern on my switch. Looks like the switches came with a few paper inserts so you could change up the patterns.
Photo from MorningGloryModerne's Etsy shop:
The listing: http://www.etsy.com/listing/178303081/vintage-nos-1950s-mid-century-honeywell?ref=shop_home_active_16
And again, the pictures of my switch. Doesn't the blue-patterned paper look like the pattern 2nd from the left on that package above?