There are all sorts of different kinds of clips and clamps. The cheapest and most commonly available clamps are ordinary household clothespins; almost everyone has at least heard of the idea of using these on nipples.
Simple clothespins make good clamps for nipples, but can be used anywhere (provided she can take the level of pain inflicted). I most frequently use them on underarms, around the breast, inner thigh and labia (pussy lips).
They come in different sizes, and can be wooden or plastic. Some have jagged teeth (have serrated edge) at the end.
They’re pretty easy find, too. You can buy them many different places, Target, Walmart, and even Lowes. I suggest you also check arts and crafts stores like Michael’s because they often have a wide variety, including tiny ones.
Smaller clothespins tend to be stronger and more painful than larger clothespins. The drawback to clothespins is that it’s difficult or impossible to control how tightly they clamp, and for some subs they are too much.
As always know her pain tolerance and limits, and introduce them slowly.
Have you used them or had them used on you? Other than nipples, where were they used? Was it a good experience?