EVA Foam
Best for: large flat or simply curved panels, budget-conscious builds, any piece that needs to be light and flexible. Strengths: extremely cheap, lightweight, widely available, fast to work with. Weaknesses: limited detail retention, softer surface than Worbla, doesn't bond to itself without adhesive.
Worbla
Best for: detailed pieces, edges and borders, small sculptural elements, pieces that need rigidity. Strengths: self-bonding, detailed surface, can be reheated and reworked, excellent for hard edges. Weaknesses: expensive relative to foam, heavy, takes longer to finish smoothly.
Foam Clay
Best for: small sculpted details, organic textures, elements that need to be shaped by hand without tools. Strengths: air-dries to a hard finish, takes fine detail, paintable after drying. Weaknesses: slow (drying time), not appropriate for large pieces, less structurally strong than Worbla after drying.
When to Use Each
Most professional builds use all three: EVA foam for large body panels; Worbla as an overlay on foam for rigidity and detail; foam clay for specific sculptural details. The material cost scales but so does the quality.