@Vicki C
A gust into your brain storm: kind of a variation of the rim part of Lisa's rimmed soap, from regular soap batter, with black hearts in the rim design. And then into the middle of the column mould, just glop in the pine tar soap, plain smooth as it is, or with just a lazy little ITP streak of charcoal batter.
Idk how converged the conceptions of your customer(s) are, if this would still be covered by specification. But AFAIK pine tar soap is unconditionally HP, and HP swirling/embed techniques are tricky.
ETA: Something close, realised in M&P
Pine tar soap does not technically have to be HP, RO. That last time I made it, I used the CP method. In spite of it being on the warm end of the spectrum, there was no 'cooking' of the soap before pouring into the mold.
I do like your rim suggestion, as that would look very nice.
Just got a commission for wedding party favors -they want pine tar soap with black hearts! I know, this is a little different. I am brainstorming. Maybe lace filigree black hearts and pour the pine tar soap over them. No time with pine tar to do anything fancy in the soap itself. Maybe cookie cutter hearts and replace with black soap? Sounds a little juvenile. Maybe have a stamp made and stamp the impression in black? I was awake at 3:30 am trying to figure it out.
Vicki, I was wondering what size the wedding favor soaps would be? Full sized soaps? Or guest-sized (sort of like travel size or hotel size)? For a wedding party, I would guess the bride would want full size soaps, because that would be such a select group.
With either, doing individual heart soaps (if you have the correct size individual molds) would make it easy, If the wedding party is not large, you'd probably only have to make 2-3 trays of heart soaps if you have a mold something like this one. I have even sliced the hearts and used the slices as embeds and that works nicely when placed on top of poured soap batter & the just push down into the batter.
Making a rim would be lovely, but of course it is so time intensive. How much time do you have for this project and how much would you charge to make it worth your time?