I'm not an expert, so I'll let someone more knowledgeable recommend DVD's or books, but I do know that depending on your needs with vary which method of holdout you'll need.
A card and a coin need different holdouts, as well as any object, and where you're wanting to retrieve the item from will all make a difference in the device.
If you're looking to grab a deck, packet, or single card there are holdouts available. There is probably a good amount of information for coins as well. Anything outside of that you may need to construct your own (though seeing one or two examples might spark your creativity).
I've also been busy, lookout for an email tonight I have a few ideas on the effect you sent me (months ago?) and I should have time to get them written tonight.