You should start from the arm base. Pine is one of the best woods to use. The size depends on your desire. In this very first step, you should plan the size, shape, and thickness carefully & wisely. What you have to do next is to attach seat mount. It should be adjusted to the measurement of the arm base you have made before.
For the next step, attaching seat frame is what you must do. It may be very delicate. Therefore, you may need to use some helps especially when flipping over & attaching it. Now, it is time to attach slat supports. Make sure that you cut the slat supports that fit. So, you have to know the proper size. In this step, you will need some tools.
Attaching middle brace is the next step. It is very important for a modern sofa. Next, attaching seat slats is what you will need to do. For the next step, you are required to attach the back slats for your DIY outdoor sofa.
Then, you are still required to attach back slat brace. You will need some brand nails and wood glue to do this. For the last step, you should finish it. You can choose your desired finish. There are so many ideas of finish for modern sofa. That is all how to make a DIY modern outdoor chair.
image source : pinterest.com