Dilay is described as 'open source, easy to use 3D sculpting application. With an update, roughly, one every 2 weeks, it is well maintained'. There are nine alternatives to Dilay for Windows, Mac, Linux, Online / Web-based and Steam. The best alternative is ZBrush. It's not free, so if you're looking for a free alternative, you could try Neobarok or Polybrush. Other great apps like Dilay are 3D-Coat (Paid), Rocket 3F (Free Personal), Autodesk Mudbox (Paid) and MeshMolder (Free).
Rocket 3F is polygonal modeller created for Concept Artists and Designers. Modeling with Rocket 3F is like drawing - very Simple and Inspiring! The Most important feature of Rocket 3F is Workflow! It is Fast Fun and Friendly!
Neobarok is a 3D modeling software aimed at artists and users of all levels. It allows you to quickly give shape to your artistic, design, or engineering ideas, to create highly complex objects using a relatively simple toolkit.
Polybrush is a new 3D editor created specifically for artists. It very useful for 3D concept art, fast modeling and sculpting. The main difference in approach to the creation of 3D models as a drawing. It was created by artist for artists.