Hello Bluehill-
I believe you are overthinking your project.
Here is a photo of my first soap cake:
It sold really well. I was worried about making the outside realistic looking.
I think the shape is so distinctive, that it convinces people. I used lemon
pound cake FO and it smelled yummy!
This was done in a plastic microwave bundt pan, and I could flex the mold
to get the soap out. I added finely ground oatmeal for texture, used M & P
for the frosting. (spray with alcohol first)
If you are going to do whipped soap for the frosting, I think you would add
that after it comes out of the mold.
This weekend I poured a chocolate one- didn't worry about texture.
I used BB's deep, dark chocolate FO and will glaze it with Chocolate drizzle FO.
Easy-Peasy Just get a good mold- I bought 2 of these at the Salvation Army
store for 50 cents each! There is also a tupperware jello mold that has inserts
that you can pop in the top (hearts, trees, etc) that I have seen at the
thrift store. Silicone molds are available on the internet for around $18.00
Here is a link to another photo of a beautiful cake by Ilovesoap:
www.soapmakingforum.com/forum/viewtopic ... highlight=
Also- you don't have to wait a couple of hours to add another layer. If I am layering,
I have all ingredients for each layer pre-measured. Bring the first layer to medium trace,
spritz it with alcohol & cover it. Mix up the batch for the second layer, pour it on top.
You don't want to risk having your layers separate later.