Is it ok to have permanent magnets in theremin case

Hi. I've built the Paia Teremax and I am making the case for it now.

I have an idea to make the lid of the box to be held in place by 4 pairs of small (5.5x5.9mm) neodymium magnets. The box is 40x18cm, the magnets would be located at about 10-12 cm from the PCB. Antennas would pass the magnets in about 2-3 cm distance.

Is it a good idea? Or would the magnets interfare with the oscillatiors or antennas and would make my Teremax inferior in any way?

Thanks for the suggestions.
-Alvis

Magnets of that size certainly shouldn't be a problem.  Neodymium magnets will behave as any other small piece of metal - they might affect the tuning slightly, but you'll probably hardly notice it.  The magnetism might only be a consideration if you placed them right near ferrite-core inductors, and even then it's doubtful you would be able to hurt your theremin.

I would say do what you want with the magnets in your box. If you have the theremin operational beforehand you can place the magnets roughly where you intend to place them to convince yourself that it's not a problem, but I wouldn't worry about it.

Thank you, @pitts8rh. 
Indeed, the best thing will be to test is before putting them permanentelly in. 
But now I will feel much more confortable to do it. 

Thanks!