A Market Constraint is an External Constraint (influenced by external sources) either on the supply or demand side. This may include a lack of available labor (supply) or the cost of a commodity that you're selling (demand).
Examples of Market Constraints may include:
Cost
Supply
Demand
Uptake
Order Quantity
Max. vs. Min
Price
Alternatives
Competitors
Shortages / Scarcity
Order Quantity
Available Labor
Hints:
Have you considered the demand for your products and services?
Don’t maximize production capacity unless you can feasibly obtain the raw materials for that capacity / production level.