If you want to add a nice project for your workshop, we recommend you to consider building a basic tool stand. There are many plans and tools you can choose from when building a tool stand, so we recommend you to work with attention and to select professional plans. There are so many things that you could build in your backyard that you really need to plan everything with attention and to invest in the best materials you can afford.
Read more about how to build a nice tool stand. Plumb the posts with a spirit level and make sure the corners are right-angled. Work with attention and invest in high quality materials, if you want to get the job done in a professional manner.
Select the wood with attention, as the slats should be in a good condition and without cracks or chops. Add waterproof glue to the joints, in order to get the job done as a professional and to enhance the rigidity of the structure.
See HERE more instructions for making a cold frame. As you can see, you can build a butterfly cold frame with two symmetrical lids, in order to create something unique in your own garden.
Leave no gaps between the slats if you aim for a very professional result. Assemble everything with great care, as the structure should be rigid and durable. Build the corner posts out of 2×2 lumber and make sure the corners are right-angled. Place a spirit level on the top beam to check if it is horizontal.