In miniature
Definition 1 of 1
Pro Tip 1/3Scaled Down
Use 'in miniature' to describe something made much smaller but still detailed or functional. 
The engineer created the bridge in miniature to test its design.
Pro Tip 2/3Exactness Matters
The phrase implies not just small size, but also a faithful reproduction of the original's features. 
The dollhouse is not just tiny; it's a Victorian mansion in miniature.
Pro Tip 3/3Metaphorical Use
'In miniature' can be used metaphorically to suggest a situation reflects a larger one. 
Little league baseball is like the major leagues in miniature.