We did the same thing as Glueguy in our 179.
Your dimensions may be different, but most wardrobe cabinets are in the 12"+/- range. the plastic covered wire shelving available in the big box stores are perfect. they are thick metal rods inside, so can be hard to cut. I used large bolt cutters and then filed the edges smooth.
I made simple 3/4"x3/4" ledgers which are plenty strong enough. I had to add an extra section because the wall was not flat on the left side .Usually the corners have a solid vertical piece on both sides. The corners are the best place to anchor the. Center areas are probably hollow with thin plywood on one or both sides.
The shelving has a built in lip that drops down below the level of the shelf. I cut my shelves so that the right side of my shelf was the back side of the original wire shelf. The left side of my shelf is the actual front edge of the original wire shelf. So, I cut the original wire shelf into lengths for my shelves that were the front to back measurements of the wardrobe cabinet. I hope this is clear. the pictures will help orientation.
Good luck
Vann
Good luck.
Vann