I don't know why I didn't think of this, but as a pest control guy, I get all my liquid chemicals from UPS. Of course, you can clearly hear/feel the liquid in the box. Probably won't with colorant.
Here's a kit I just found on Amazon
https://www.amazon.com/JDiction-Silicone-Molds-Making-Manual/dp/B08ZCDT63L/ref=asc_df_B08ZCDT63L/?tag=hyprod-20&linkCode=df0&hvadid=663271582232&hvpos=&hvnetw=g&hvrand=17986420754261790022&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9031864&hvtargid=pla-2216265738164&mcid=c5fa1f774a0438fb9778e9fb3976d5e4&th=1
Back when I did this, I couldn't find anything softer than MF super soft. Don't know why you'd need anything softer than that. But like the others have said, to save your current batch, softener will do the trick.