If you don't a shutter, might I suggest homemade drop shutter . . .
I have taken photographs with a homemade 8x10 by turning the lights on and off. It's as effective as a shutter. But, those were paper negatives and the exposures took a long time, ie; minutes.
You can also make your own stops and place them in front or behind the lens. It should work fine. For sharpness, the thinner the material and the more perfect the hole the better. But don't stop there, you can make stops any shape you desire . . .square, oval, triangle, star shaped, or the common circle. Experiment, and have fun.