Take measurements of the place you will be using the molding so you know how long of a T-molding to cut. This could mean measuring the opening of the door or entryway to another room or along the place where your floor is transitioning.
Use a jointer to flatten the edges before cutting your board or rip the edges on a table saw, making sure the rip fence is parallel with the blade. A jointer is a tool used in woodworking to smooth and flatten out rough edges of wood; it has an infeed and outfeed, a fence to keep wood in place and a cutter to smooth out the surface. Wood goes into the infeed between the fence and the cutter head and a motor makes the cutter head spin, causing the head's sharp knives to remove any raised areas or ridges and flattening its surface
Choose your tools. One option is to use a table saw with a molding head cutter, a special attachment that allows the saw to make rounded precision cuts necessary for molding. Another option is to use a router, which is a special hand-held or power cutting tool that is shaped to allow you to make grooves when doing woodworking projects. Of the two, the router is considered the safer and cheaper option because the assortment of bits that allow you to take out smaller pieces of wood and gives you a greater variety of cuts to choose from.
Make the cut. Pass the wood into the router on its edge or face, holding it against the fence. The height of the router bit affects cut shape as does the distance from the fence. The farther the distance, the longer and wider the T-molding will become.