I would love to hear some suggestions regarding an undercoat on a dummy cake that will make putting the fondant on easier. I have only ever tried piping gel????

I would like the answer to this question too. And can you scrape off the fondant after taking pictures, or just practicing, and use the dummy again and again?
 

Lots of people use just plain old water.  Wet the dummy then cover with fondant.

My personal preference is a thin brushing of piping gel.

I know someone who uses slightly watered down boiled jam (cheaper than piping gel).

Yes, once you've finished with your dummy cake, you can take off the fondant and use it again!  In fact I have 4 wedding cake dummies that I'm in the process of doing that with.  After separating the tiers, I filled my kitchen sink with water and then left them to soak in there for a while.  That softened it enough for me to be able to slip a palette knife in between the fondant and the dummy.  It came off almost in one go!

On other occasions, I've put the covered dummy into the dish washer!!!!!  It comes off a treat! 
 

I am laughing at the one that went into the dishwasher! I would never have thought of doing that!! Thanks Relznik! I love hearing what others use.

AGood old H2O. I fill up a new spray bottle and spitz away.

If I'm not happy or want to start over I simply carve lines across the top of the dummy, mimicking cak.slices and peel them off

I use watered down corn syrup, a bit easier to apply than piping gel, and costs pennies. I just brush it on with a pastry brush.

I don't usually reuse mine, simply because I can get them so cheaply, it's not worth the hassle, lol. I have just recovered a couple right over the first layer fondant though, lol. (I'm lazy)

I use Copha - Aussie equivalent to Crisco

Makes removal pretty easy
 

ACrisco

ACrisco. And I usually forget to remove the fondant from my dummies for at least a couple of weeks, and I put it in a trash bag and lightly whack it with a mallet to crack it off. Easy peasy.

Good ol' Crisco.

It is so great to have CC & everyone who has such good ideas willing to share them!

I will use cheap decorator icing, but I know it's not cost effective. I will need to try something different from now on. I do, however, wrap my dummy styrofoam tightly in plastic wrap before I coat it, then cover with fondant.

Good idea IAmPamCakes!

Just a spritz of water.

Yep! Just plain old water!