How many different walls can be made using just rods of two colours?

Have a look at these examples - how would you make the next wall?

cuboids only 1 unit wide made from rods of two different colours

Now take a third rod as well.

What different walls can you make now?

What different solids can you make with $3$, $4$, $5$ ... rods?

different solids made of various length rods