A page full of dots, a cloud of text labels, boxes. It is hard to make things look "random".
I try to replicate the effect of shaking a glass box full of cookies in a different color. Copy paste your presentation objects on the slide. Then start moving them around. Resize to make them more or less the same size. Avoid clusters/clots of similar shapes or similar colors on the page. Take a step (or 3) back from the screen and see how it looks, repeat the above process again.
Randomness is actually a very organized state.
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