[dataweaver]

How about this:

Morph (Mass Conservation, -20%; Retains Shape, -20%) [60], plus up to another -40% in limitations, for a cost as low as 20 points. For insurance, “can only reallocate attributes”, or “cosmetic changes cannot exceed what's possible for Elastic Skin” (which would actually replace and subsume both Mass Conservation and Retains Shape, and so would be worth at least -40%, but less than -80%). Or Minimum Duration (up to 8 hours, -5%): once you've altered your form, you must wait (up to) 8 hours before you can shift again. As the GM, you may rule that that's 5 hours, not 8.

This doesn't give you any additional points for attributes; but it lets you rearrange the ones you have to your heart's content, limited only by the fact that the attributes must be appropriate for whatever cosmetic changes you've made. Basically, it works on a “Rob Peter to pay Paul” basis: if you're going for a form with more ST, you'll need to lose some DX and/or HT (or appropriate Secondary Characteristics) in compensation.

This would replace Elastic Skin; so if you just go with the bare-bones model described above, you're only paying 40 points to rearrange your attribute points freely. That's why “cosmetic changes can't exceed Elastic Skin” can't be as high as -80%: you're getting more utility than you would from Elastic Skin, so you should pay more for it than the 20 points that Elastic Skin costs. That said, it probably would be worth more than -40%, as there are some restrictions on Elastic Skin that aren't covered by Mass Conservation or Retains Shape: for instance, Elastic Skin doesn't let you change your wardrobe: you're wearing what you're wearing.