I recently bought a Polaroid 340 Land Camera and since I already have the 100 version I knew I needed to convert the battery compartment to take modern day batteries, three AAA's in fact. Here's how I did it.
First of all you need to get into the battery compartment found on the reverse on the left. Once opened you'll find two wires and plastic grips which would have held the original battery. This was where I forgot to take a photo before taking two of the grips out...
I used some jewellery pliers to removed the plastic, it's quite soft so doesn't take much effort.
Next you need to find a battery container that you can link to the camera, the most compact version is the one of a handheld torch, mine was bought from the Poundshop,
If I had a soldering iron I would have used that to join the battery holder to the wires but alas, I don't so it's down to good old fashioned electrical tape. You want to make sure that the white wire goes to the plus side of the holder, and the black to the negative (also that you put the batteries in before taping up!).
Then with a bit more tape on both the negative side and positive to make sure it doesn't move, place the batteries in and close it up.
You'll need some Fujifilm FP100-C film (or the elusive 3000C film) I buy mine from Ebay in bulk and store in the fridge. I put the film in and used one of my willing models to see if my handywork worked.
The brilliant thing about this model compared to my 100 is that there is a separate lens for making sure the subject is in focus, something I've had to guess in the past. Also, I happened to find a close up kit for this model which I was eager to try. With the standard model lens the closest you can get to a subject is about 3.5 foot, with the close up kit the range is 9 to 15 inches. I got my willing model again, I can't explain how exciting it was to take a shot with a Polaroid this close after 2+ years of my model 100.
Once I have my flash gun fixed (now that does need a soldering iron!) I can keep experimenting both outside and inside, here's to the 340!