How to Demonstrate Light Pressure?

Crookes radiometer. wikipedia.org/wiki/Crookes_radiometer.

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Though I'm not sure light pressure is completely accurate for that phenomenon. It's a demonstration at least.

I want to demonstrate light pressure,but the value of the light pressure is too small.

You can "fake it" with a radiometer. It really works because there is still a tiny bit of air that rebounds from the blackened side of the vanes that becomes warmer when light falls on it, not because of the momentum of the light photons.

That's a good idea. The only hurdle is the high vacuum for the blade space to minimize the effects of heated particles.

So instead of making it himself, the OP commissions a 'custom radiometer' from a company that makes them, ordering one with all silver surfaces instead of silver & black.

When in doubt, let the people who are experts in building the tools build the tools, instead of trying to build the tools yourself⁽¹⁾.

Notes:

1. Which for more complex tools, such as a radiometer, means buying/building the tools to make the tools, going down several iterations in required, this may be fun for some people⁽²⁾, but for most, it's considered a wast of time and energy, unless the 'building the tools to build the tools' is being done as a learning exercise to better understand the tools themselves.
2. And those people who like to build tools to build better tools can get their fun by playing any one of those exploration/survival/civilization-building games with a 'tech tree' in it. All the fun of inventing the wheel to invent chariots to invent trains to invent tanks, without having to take up the entire garage with the project.
   

Have you considered increasing the power of the light source to help increase the effect and thereby use a less complex measuring device?

Also, I know this is just common sense but if you only want to demonstrate the phenomenon have you considered just downloading a video of YouTube or the internet of the phenomenon being demonstrated?

The experiments by Nichols and Hull in the Dartmouth Article appear precisely on point.