Kitchen garden inspiration - build an Amish cold frame. I love this clever design. No plans available (our Amish friends didn't even use plans to build our sheep barn), but there are 10 photos in this post showing construction details.
Rosemoor Greenhouse 6 - 8 with Coldframes - All the greenhouses in the RHS Collection are designed in such a way to easily accept cold frames. The cold frames can be placed on either side of the greenhouse or both if you prefer - Gabriel Ash