If you don't want to buy any tools (which are totally worth their price, BTW), you can always interrogate the system catalog views, and extract the info from there to create scripts you could execute on your new database.
In the case of e.g. the default constraints, this query shows you a list of all the default constraints in your database:
SELECT
dc.name 'Constraint Name',
OBJECT_NAME(parent_object_id) 'Table Name',
c.name 'Column Name',
definition
FROM sys.default_constraints dc
INNER JOIN sys.columns c ON dc.parent_object_id = c.object_id AND dc.parent_column_id = c.column_id
ORDER BY OBJECT_NAME(parent_object_id), c.name
and based on that, you could of course create a query which would emit T-SQL statements to recreate those default constraints on your target server:
SELECT
'ALTER TABLE dbo.' + OBJECT_NAME(parent_object_id) +
' ADD CONSTRAINT ' + dc.name + ' DEFAULT(' + definition
+ ') FOR ' + c.name
FROM sys.default_constraints dc
INNER JOIN sys.columns c ON dc.parent_object_id = c.object_id AND dc.parent_column_id = c.column_id
You'd get something like this (for the AdventureWorks sample DB):
ALTER TABLE dbo.Store ADD CONSTRAINT DF_Store_rowguid DEFAULT((newid())) FOR rowguid
ALTER TABLE dbo.Store ADD CONSTRAINT DF_Store_ModifiedDate DEFAULT((getdate())) FOR ModifiedDate
ALTER TABLE dbo.ProductPhoto ADD CONSTRAINT DF_ProductPhoto_ModifiedDate DEFAULT((getdate())) FOR ModifiedDate
ALTER TABLE dbo.ProductProductPhoto ADD CONSTRAINT DF_ProductProductPhoto_Primary DEFAULT(((0))) FOR Primary
ALTER TABLE dbo.ProductProductPhoto ADD CONSTRAINT DF_ProductProductPhoto_ModifiedDate DEFAULT((getdate())) FOR ModifiedDate
ALTER TABLE dbo.StoreContact ADD CONSTRAINT DF_StoreContact_rowguid DEFAULT((newid())) FOR rowguid
ALTER TABLE dbo.StoreContact ADD CONSTRAINT DF_StoreContact_ModifiedDate DEFAULT((getdate())) FOR ModifiedDate
ALTER TABLE dbo.Address ADD CONSTRAINT DF_Address_rowguid DEFAULT((newid())) FOR rowguid
Of course, you could tweak the resulting T-SQL being output to your liking - but basically, copy&paste those results from the query to your new database, and off you go.
Of course, there are similar system catalog views for foreign key relationships (sys.foreign_keys), check constraints (sys.check_constraints), indexes (sys.indexes and sys.index_columns) and many more.
It's a bit of work - but it can be done on your own time, and you'll learn a lot about SQL Server in the process.
So it's a traditional "make or buy" decision all over again :-)
Marc