If you have a profit motive, then showing your custom bike would count as a business.
There is a catch here. The IRS expects to see a profit. If you lose money more than two out of five years, the IRS may question your profit motive and claim this is really a hobby.
Hobby expenses are deductible only to the extent of your hobby income. You can have a loss if it's a business, but not if it's a hobby.
This article explains more about how the IRS views the
difference between a business and a hobby.
