Not sure what you mean with regards to "slight movements".I upgraded my projector a while back and it can do 3D. I was never interested in 3D, I just got a good deal and bought it and 3D was a bonus. But recently thought my girls would love this outdoors. They are 4 and 6.
I have 100 inch sheet that I used to hang on my swing set. The swing set went away so I either need to build a frame for it or get something else. If I buy something else, I'd like to step up to 150 inch or so screen. Budget...not sure, but I'd be willing spend a few hundred dollars or so if it is worth it.
Question 1: Will the slight movements impact 3D?
Question 2: For 3D, thoughts on the sheets, inflatables, or something else?
Thanks in advance
Take a look at Carl's Place for a screen/screen kit. Very good product at a reasonable price.
Standing Projection Screen Kit (carlofet.com)
Because of the way 3D works with active glasses, you want a bright image.
Additionally, moving from a 100" screen to a 150" screen is a big size increase, almost a 45% increase in size. So you want to make sure that your projector is capable.