I am building an app exchange app and I want to transfer orders into a custom Salesforce object called invoice. How can I export the custom object, without any data, into another user's Salesforce? I have a developer edition of Salesforce.
Create either a managed or unmanaged package with the custom object in it. Then install that package in the target org. Unmanaged is good if you just want a one off transfer of metadata with no upgrade path. A managed package will give you an upgrade path for most components, but will also lock other components into their current configuration.
The alternative is to use the Metadata API to export the schema and then import it again. There are a number of developer tools that support this. The Force.com IDE is one of them.