Particleboard and MDF, Which Are Chips and Fiber
Both start as wood broken down and pressed back together with adhesive, particleboard from chips and sawdust, MDF from much finer fiber.
Both are dimensionally stable and inexpensive, and MDF is smooth enough to take paint better than real timber does, which is why painted furniture and molding so often use it on purpose rather than as a compromise.
The limit is load and water. Neither has continuous grain to lend it strength, so a long shelf bends without ever breaking, and both swell permanently once moisture reaches the core.