I have no idea what a 'bundt' is, but layers I can help with!!
To do a layered soap, I usually divide my normal batch by however many layers I want, and make each layer seperately.
For example, if I want to do 3 layers in my TOG block mold, I will divide my normal batch for the mold by 3 to get the amount of oils, lye etc for each layer. I will make the first layer & color & scent it, put it in the mold.
Then I make the batch for the 2nd layer, color & scent it & carefully pour into the mold, trying not to disturb the 1st layer too much.
I then make the batch for the 3rd layer, color & scent it & carefully pour into the mold, trying not to disturb the 2nd layer too much.
I mix each layer until thick trace before putting into the mold, so that they are kind of firm when pouring the next layer. Does that make sense?