Papyrus
What would you do right now if someone told you that you needed to run out to the store, buy some papyrus, a brush, some ink supplies and start writing in Sanskrit? That’s what I had to do. My plans, the designs for the time machine were provided to me, by me, from me.
Once when I was a bit younger, I “figured out” how to make it work, tested it, and successfully traveled back in time. Then I only had to make sure to put the designs for it in the place where I originally found them.
Of course shortly I realized, I had a time machine. If I really had to go somewhere and find some papyrus and all the necessary accessories to write on it, I could just go back in time to when all of those things were available. So that’s what I did. I went back in time, got the same type of media I had originally found…