Forty-scale aircraft are a Czech institution. The format comes from a generation of locally tooled kits that taught several decades of modellers how to hold a knife, and it survives today in exactly that spirit: modest parts counts, forgiving fits and subjects chosen for charm rather than complexity. A Spad VII or a Fokker S11 trainer in 1:40 goes together over a couple of evenings, which makes it a sensible first aeroplane for a child and a genuinely nostalgic return for anyone who built these as a teenager.
For a first build it helps to add a starter set with paints, which puts colours, glue and a brush in the same box. When the next model calls for more detail, the widest choice of subjects waits in 1:48 aircraft kits, and the whole catalogue by scale is listed under aircraft model kits.