1- purchase pre-con with assignment clause.
You can purchase pre-construction from the builder and sell it before the completion date with a profit.
make sure the builder allows assignment. If they do allow finding out cost of the assignment.
Keep in my you may not be able to assign it to someone else therefore you are responsible for financing.
2- lend your money. this is VERY RISKY if you have no experience. You can make 10-15% interest per year.