is this a possile DIY project?

I have lots of telephone cable and some spare time.

If I strip the outer casing from the phone lines, twist them properly, and add the right connections on the ends will I have usable cat5 cable?

 

Interesting, you could try using the wire without stripping it all and re-twisting it. You only need the orange and green pairs.
So like try red & green on pins 1&2 & yellow and black on pins 3&6 for both ends and test it out.
Let us know how / if it works.

 

I thought thats what the inmates of Florida State Penitentiary did as a passtime. MA?

 

You would Not get Cat5e by doing it, you would get twisted telphone wire that might or might not transfer network traffic.

If it would transfer it would be at a lost of big part of the bandwidth.

BTW, most none-pro cable makers get partially functional network cable even if they do buy Cat5e and crimp it themselves.

 

Perhaps you'd elaborate further?