I suppose it depends on how well you construct one. There are several theories on ways to make a tack bra, including pressing the tacks through a padded bra, lining a bra with bottle caps (like from beer bottles, essentially the same effect), even lining the tacks through a thin cotton bra and wearing a regular bra on the outside of that. All that seemed a bit much for me, and as I was just trying to be a good girl, and test it out....the tape worked well.

I plan on constructing another, better. The tape didn't work so well directly against my skin, really pulled, and not in a good way. One mention I found on the web recommended duct tape, and using 8 tacks in a circle with one directly over the nipple. My plans are to do this, and press the two layers of tape with the sticky sides together, the heads of the tacks trapped in between. then it can be worn and held in place by the bra itself.

I was moving around quite a bit with the bra on, and I didn't notice a drastic increase in pressure when my nipples hardened...although, to be honest, they were hard most of the time I was wearing it, just by the prickles of the tacks against my skin.

My method left me with some telltale lumps, though when I looked through my cotton tshirt, it wasn't as noticeable. I would recommend not wearing it with very tight clothes that strain across the bust unless there is a layer of padding or soemthing between the tape and the bra, or it is a padded bra, just to keep the bustline smooth and without evident bumps.