What's an etsy mini? It's like a little treasury, but it only contains your etsy items. You can also make one with your etsy favorites by other sellers. I have one on this blog, it's in the box titled "My creations for sale".
Go to etsy.com and sign in. Click on "Your etsy" on the top of the page. On the left hand side click "Etsy Mini" (it's under Promote). Click "Items from my shop" and then "Thumbnail" or "Gallery". Choose layout (I think most people go with the default).
Then sign into your blogger/blogspot account. Click "Layout". You'll see on the right side a link in a little box saying "Add a Gadget". Click that. A window should pop up.
Click Save. The pop up window should close and you'll be back to your layout page.
Important: Now click the big orange "save button".
Hope this helps!