3 resin questions

1. How strong is resin compared to plastic? I'm asking be cause i'm planning on casting a replacment part for a window latch. I figure it depends on the type, so what are some strong resins?

2. If i were to do an open top mold could i fill it half way, put a small loop of wire (for stregth) , then continue to fill it to the top? or should i let the bottom half semi harden to prevent the wire from drifting.

This is a top view with thewire being into your screen half the depth of the part:
http://i6.photobucket.com/albums/y232/ToyTundra/part.jpg

3. Is resin temerature sensitive? Will it get soft or brittle in extreme heat/cold. Heat is up to 170 F (76 C); cold would be below freezing

Resin is relatively brittle at all temperatures. What kind of window latch are you trying to make? By your description, I think resin is probably not the material to use.

Depends on how much stress is on this part. The wire loop is a good idea, but if the resin should fail the wire would simply pull out since it isn't a continous loop. If it's a simple latch that swings back and forth, resin would be a decent choice. Is this part irreplaceable? Is it an aftermarket part that could be obtained from the manufacturer? How big is this? How many do you need? You could probably make that cheaper and easier with plastic stock, a drill press and a belt sander, if you have access to such tools. Even a regular file and drill would probably get you there. Another option is sending a draft of the piece to a machine shop and having them make it for you out of any material you desire.

Here's an example of different types of resins. http://www.smooth-on.com/plastics.asp

It's a common part that fails on the Tundra. The dealer does stock parts, but they are identical. I am trying to make a stonger than stock part to distribute, so i would like to make around 100. The long side is about an inch long.
I am open to materials (plastics, aluminium, etc) and have access to CAD/knowledge to use it so machining is not out of the question, but i would like to keep the overhead low so i'm not in the poor house.

Here's a pic of the the latch most of the way open
http://i6.photobucket.com/albums/y232/ToyTundra/windowlatch.jpg

And a broken one (its on the other side of the truck)
http://i6.photobucket.com/albums/y232/ToyTundra/windowlatchbroken.jpg

No way. :disappoin A resin part would fail on the first closing of the window, and the wire wouldn't add any real strength. For this kind of part, think machined aluminum, or maybe nylon. Unless you're set up for CNC machining, there's not going to be much of a profit margin.

i would beleive that aluminum is the best option here.

Lots of tension and compression on that part, no way any normal resin would hold up. Another idea would be a stamped piece that spans along the original part, going from hole to hole. Basically the same dimensions, except it'll only be ~1mm thick to support the stock piece. I imagine that would be cheaper, but with such low volume you'd still be out of any profit.