This guide will let you know how to Combine Items and craft something new in Sons of the Forest.
You have to go to duct tape, right-click on it and you will get the option to combine. After that right-click on the knife to put it on the platform and then look for the sticks.
Right-click on the sticks and combine all those things to craft a Cog. When it is ready, right-click it and right-click on the duct tape and it will show you all the options.