"redneck way would be to hot glue two oil bottle caps together then drill a hole in the middle. Your glue job would have to be perfect to prevent any leaks"
Now see, that's one heckuva good idea, & if we can find a glue that will actually work it's a *great* idea.
I was thinking in terms of drilling out 2 caps, then connecting them with one of those big copper grommets for tarps. Problem is, I don't have a drill bit that big, or the copper grommets, or the "crimp it with a hammer" tool for that. Guess I'm just too "old school" & seldom think of adhesives.
So, what kind of glue? Hot glue? Epoxy? JB Weld? Super Glue?
If we could get a *good* glue bond, then drill it, then wrap the outside with big shrink wrap, or good electrical tape, or duct tape, it would work perfectly & be Free!
Almost forgot: Speaking of "good to the last drop" oil drainers:
Found the Ketchup Saver at a kitchen knick-knack store in Longview on Friday- cost was $3, & it has *3* different threads in each end!
I never knew about the multiple threads. That alone makes it worth $2-$3, IMO. Heck, the largest thread might screw onto a gallon or 5-qt motor oil jug- but it looks kinda small. Gotta go try that now!
So, keep on lookin' & figurin'- no telling what you might find, or invent!