Thanks, Faith -- those are good thoughts. I'm making individual bars as gifts for people whom I know well, so I think I'm going to go ahead and see what happens!
Most embeddables that I see are soft rubber or soap. I would like to make some gift soaps for specific individuals and would really like to use the great novelty plastic buttons you find in craft and fabric stores as embeds. I use them for scrapbooking by clipping the shank off the back...