Circular Light Diffuser Like This One

Years ago I purchased several circular light diffusers, similar to the attached image.
They're lightweight plastic. Very durable. I'm 90% certain they were for circular
flourescent bulbs. I found them stacked on a shelf in a hardware store, so I can't be
100% certain what they were manufactured for. It's hard to see in the image, but there
is a center hole for a threaded hanger rod.

OD (outside diameter) measurements are 10-1/8 x 3-5/8 inches.

I REALLY need to find replacements! I have decent shop, so I can drill accurate holes
or cut plastic if needed. I've visited several local businesses. No luck so far. Rather
than search the web for hours, I'm hoping an expert can point my browser in the right
direction.

I'm trying to think "out-of-the-box." Heat is no longer a problem (LED bulbs). For
example, there are zillions of translucent plastic containers that could be converted
to a circular light diffuser in my shop. The only requirement is a flat bottom. It must
be shaped like an upside down birthday cake. I can't use a globe style bulb cover.

 

Try here:

Puffs & Drums - Lightcovers

Failing that, it rather looks like the cover of a Tupperware cake taker....