You can make them using the construction skill and some runes. (And the appropriate level to cast the spell itself)
The advantage of teleport tablets is so that you can use the teleport to get to a certain location with the level not required, and you won't get any magic experience for it. This is especially good for players like me, who are level three skillers and cannot raise their magic level, but would still want a decent traveling method.
If you get a high enough construction level, you are able to build a lecturn inside your house. When you do this you'll be able to start making your tabs. All you'll need is one soft clay, and the appropriate runes to make your desired teleport. (And the magic level required) When you make these tablets, it's almost just like casting the spell. You'll lose your runes and your soft clay, and you'll gain the magic experience.
It's a terrific method if you want to get some magic experience but save your teleports for later. They also come in handy to sell for cold hard cash in the end!
Good luck with your tab making, Best of luck in the future in RuneScape!
-Sibley Tutor
