Speaking as someone in the midst of building a Warlord Titan, I can fairly well say that plans do not exist for almost any titans. The only ones I am aware of are for the smaller Reaver and Warhound titans. They are available at
a place called Paperhammer40k
My best advice is for you to find a set of pictures from forward top and side perspectives.
Print them out to scale on giant paper (or just splice together a bunch of print outs)
Wing it.
Seriously, some people spend years just trying to figure out precise plans, but if you are just looking for something to impress your friends with you really just need to get some materials together, figure out what you want to make, and just get go for it.
Good luck
Also, a link to my titan is below.