Trending Nail Ideas Coffin Shape Medium : Coffin nails — or ballerina pointe shoe nails, if you're squeamish — have a flat top and straight sides that slope inward, just like their namesake. Negative space, moon manicure and varied french, geometry and minimalism. Nail Ideas Coffin Shape Medium - They are a great solution for long nails, and can be achieved through artificial (acrylic) or natural means.