I (probably like most) have tried various things when I don't have the right gear.  I thought it might be good (if we can stand the humiliation) to post em up so everyone can see what works and what doesn't.  I'll start.

I've tried covering a plug in vinyl to give a good surface as I was too lazy to seal it and paint it properly.  I tried airelease vinyl that had several coats of wax on it and I got away with it.  Yay!  I tried a cheaper vinyl and it wrinkles like mad.  I tried the airelease with fewer wax coats and got a slight bubbling.  Worked once but probably not something I'll chance again.

I used 'antique pine' wax once when I'd run out of proper mould release.

I once used car body polish and wax as release agent for a bonnet I was doing, and it actually worked really well!

Reused bagging tape and vac bag once... Worked fine  

I always re use bagging! Didn't realise it was pikey!

Yeh I didn't really consider reusing the bag too dodgy, more the sealant tape. Used to have a big ball of used tape that I cut chunks from. Just had to watch out for the fragments of cured resin, they weren't friendly for leaks

I'm rather suspiscious that car waxes and mould waxes are rather similar in composition.  I have wondered how my paint would fare with a coat of easylease.  Might also help get brake dust off the wheels!

I have used easy lease on one of my bonnets and it gave it a hell of a shine, however it haven't driven the car since so not tested its anti dirt properties!

Not the worst and hopefully the wife won't come on here, but ran out of talc the other day when mixing up bog so stole a bottle of Johnson's baby powder from our nursary and used that instead, then denied all knowledge of where half the powder went.

Don't try using a DA sander with 120 grit on your curved part!

Doh!

Took many hours to get the scratches out.