Fewer than most founders initially want.
Each new size can create additional requirements for:
- formulation;
- thickness;
- tooling;
- packaging;
- artwork;
- testing;
- certification;
- inventory;
- forecasting;
- advertising;
- customer support.
I would start with one hero product and a small number of closely related selling units.
For example, one dog-waste bag format could be sold as a refill, a dispenser kit, and a larger subscription pack without creating three completely different material platforms.
Expansion should follow evidence: repeat purchase, low complaint rates, stable production, and a clear channel opportunity.