The traditional merch problem is that you have to guess. You order a hundred shirts in five sizes, and you find out afterwards which ones your audience actually wanted. Print-on-demand removes the guess by producing each item only once it sells.
The trade-off
Per-unit cost is higher than bulk printing, so your margin per shirt is thinner. What you get back is that you carry no stock, no unsold sizes, and no upfront spend.
- Bulk — better margin, real risk, cash committed up front
- On demand — thinner margin, no risk, unlimited designs
Make the artwork work
Most rejected designs fail for the same few reasons. Export at 300 DPI, keep the background transparent, and leave a safe margin around the print area so nothing important gets trimmed.
Start narrow
Put up three designs rather than twelve. Watch which one sells for a month, then order that one in bulk once demand is proven. Let the catalogue earn its way into production.