I've done bears as remembrance items very successfully. The problems with them arose when I found that the fabrics were basically cotton knits. I used fusible woven interfacing to stabilize each of the pieces of fabric I cut from the garments. After I cut the pattern pieces for the bears and got them sewn together, there was enough body to do the mouths using regular embroidery floss without any puckering. I used purchased bear eyes from a local craft store since these bears were for adults.
I wish I could remember what kind of woven interfacing I used. The brand name escapes me, but I know I need another bolt or two for t-shirt quilts in the near future.