There are many companies that produce figures in kit form made of various small pieces that can be glued. Making and painting these figures is an specialized hobby.
Airfix
3501 British 8th Army
The bases of this figure was made from bits of plastic from other figures, sand and small pebbles.
3502 German Afrika Korps
3585 British Infantry (IIWW)
55210 German Infantry (IIWW)
These figures were glued on wood bases.