So not sure if any one is still looking at this but I have finally finished my design for my wine rack. My only question is how to attach all the cross members and rails. Originally I was going to use all mortise and tenons then I realized I would have 32 of them to do. That would be good practice as I am still new to mortise and tenons but it would also be very time consuming. I may still do them for the practice, look, and strength. But I was wondering if any one had any other suggestions for how to attach them.
Does your friend have a small child or grandchild, or a dog? Given the cost of an incident, this deserves more stability. Make it easy for your friend to attach it to the wall. drill 1/4" holes in the back apron every 1/2". That will let him or her hit a stud easily.
If you add a back panel it will help.
It is important to get the bottles (in all their creative shapes) level. Mock up the supports and test them out. Don't trust designs by Ikea to work right.