You said you have mango, shea, cocoa, avocado, castor, coconut, jojoba, almond, grape seed, wheat germ...
Butters --
Greasy vs. dry: Mango butter is a dry feeling butter. Shea butter is definitely greasier. Cocoa butter is in the middle, in my opinion.
Firmness: Cocoa butter will give the firmest product. Mango will be medium, and shea the softest.
Liquid oils --
Lighter, more absorbent: Coconut, jojoba, grapeseed
Greasier, less absorbent: Almond, avocado, castor, wheatgerm
A lip balm needs to be firm and "dry" enough to be packaged in a twist-up tube, not melt in the pocket, and coat the lips with a long-lasting protective barrier. I'd say the typical lip balm would not work well as a massage bar -- it will be too firm and feel too sticky and draggy. You are going to have to find a balance between "firm enough" to remain in a bar form and "soft enough" to glide nicely over the skin, melting just enough with body heat. That will take some experimenting.
If you want a softer product that is not overly sticky or greasy, go lower on the beeswax and try increasing the butters. I would use mostly cocoa butter and maybe the last of your mango butter, if you have any left. I might not use any shea or I would keep it to a small percentage of the butters. With a cocoa butter base for your massage bar, you might find you won't need any beeswax at all.
To keep the product as light as possible, the main liquid oils should be one or two of the "lighter" oils listed above. I'm fond of coconut and jojoba -- grapeseed has too short of a shelf life for me. You could use a bit of the heavier oils to add some "glide" to your product. Of the heavier oils you have on hand, I would probably use a bit of almond or avocado. Castor is a humectant (attracts water) and can feel sticky. Wheatgerm does not have a long enough shelf life.
As always, there are a bazillion recipes that would make a nice massage bar. I'm just tossing out some ideas to spark your creativity. I'm sure there are other suggestions equally as good, so YMMV and all that. I hope this helps!
