Okayyy I know the deal with taking acetone and plastic shavings to make repair media for grills and tail lights but...

What can you do if theres no spare item to get shavings from?

My situation is my 72's rear tail light, a buddy of mine whacked it with the soap brush at the car wash and cracked it up in the corner.

Now seeing as I only have those two tail lights in the car and nothing for donor material, can I grab something similar at the junk yard or is the composition different?