Exactly translucent .Unless your wanting to make real soap, this might be best cast from a translucent resin with a pink pigment. You are referring to the soap bar with Fight Club on? If so, that is pretty cool. I'm sure there are many talented casters here that could make these. I am keen to learn how to do this stuff myself (cast parts) as well, so might be an interesting learning curve project.
Those are cool. not sure what to add into the resin to give the effect of the fat swirls inside the bar though. How about you make it I buy it lolHere are some options for the prop:
This is cool (it is soap) and would be ideal to make a mold for a re-cast for resin from. Making an original mold might be tricky or get expensive to get that font right.
I need to watch this awesome film again as I am sure he presents "Susan" with soap that is wrapped like this