Some time ago I modded a Polaroid 80A to make me able to use it with 120 film. My main reasons for doing so were: 1) I wanted to use the camera even though it had an obsolete film format, giving it a new life, and: 2) it is a very advanced camera for what you pay for (nowadays).
The first photo in this post is one of the first successful exposures I made with the camera. There were three unsuccessful rolls before that, since I used a method of film transport that didn't work (see this post).
Initially I didn't have a display window for the exposure counting (which displays the number of photos on the backing paper of the film) so wound on by approximation. Eventually I drilled a hole on the back of the camera to be able to see the numbers and to economize film. There are five (5) layers of metal to breach to make that hole!
This one was wildly overexposed. I rendered it in b&w to make it look nicer.
The same with this one.
And this one. The recent four are Ektachrome 64 cross-processed in C-41.
My winding issues didn't stop there, though. By some leap of imagination I'd settled for drilling a hole displaying the numbering for those exposing 4,5x6 cm photos, not 9x6, which is what this camera does. It took me two rolls to aquaint me with the issue and remembering to compensate for it by winding that extra bit not to get double-exposures. (Though some of those are rather nice-looking.)
Above is an almost successful full-frame exposure, with some double-exposure issue to the left.
Actually, the lens turns out to be the biggest surprise of this €30 camera: It has sharp and evenly distributed focus, even in the corners. I wanted a lens (as I always do) with interesting bokeh/out-of-focus characteristics. I think I got that in the deal, along with a high quality lens.
Another two - beautifully rendered - double-exposure disturbed crops of photos.
The exposure above is the first non-double exposure - and the last one on roll #2 after I'd made the frame-counter window. It depicts my then half-finished allotment, where I'll be growing vegetables this season.
Below you can see the best photo from a roll without unintended double-exposures. I am very happy with the outcome!
I wish that this post has taught you some things: Act before you think; do rather than don't; and have fun while doing it!