Designing a nanite does not require the Bot Building skill. However, creating a nanite is not free, the cost depends on the type of nanite. Designing and creating a trait chip requires at least Level 1 Bot Building skill; the exact level required depends on the chip. Creating or customizing a Plumbot requires at least Level 2 Bot Building skill. Creating a Plumbot costs §250, while customizing an existing Plumbot costs §100.