Hi

I was just wondering if it was absolutely necessary to cut the fresnel, except to make the box smaller?

I guess the short answer is No... but hey, I'm still learning...

Thx

No, you don't need to cut it unless, as you mentioned, you want to make your box smaller.
You just need to make sure that the center of all of your components line up (lamp arc, fresnels, LCD and triplet).

Bingo.

Of course, most people DO want to have a smaller box, and so...

Would a fresnel from an old ohp work, the fresnel seems to be glued together also how do i cut plastic? with jig saw

You would get better search results for a question like this by using the Google search terms: site:lumenlab.com +ohp +fresnel +cut
http://www.google.ca/search?hl=en&q=si...earch&meta=

Thanks didn't know goolge can be so powerful.

Yes, Google can be quite powerful.

See the following page for more information on how to search more effectively using Google:
http://www.google.com/help/cheatsheet.html

And here's a complete list of Advanced Search Operators:
http://www.google.com/help/operators.html