Does the lid "pop?"

I got a letter from a reader asking about the fit of lids....

I have been following your designs from the book Basic Box Making, and am learning so very much.  Thanks so much for sharing your passion, skill, and expertise.

I do have one quick question about the small boxes with lift off lids.  How tight of a fit do you usually make the lids.  I have been in a bit of disagreement with a fellow beginning box maker, so I was wondering what you have found to be best.  Do you think people prefer a lid to slide off quite easily, or come off with a “pop?”  I know its probably a silly question, but it is one which has kept me worried about how best to cut the lip on my lids.

Thanks so much for all you do to inspire!  

I would remember that wood is a living material, even after its cut and dried, in that it expands and contracts across its width due to changes in moisture content in the air. Build too tight, and expansion can push joints apart under extreme conditions. What may fit with a “pop” today may not even open tomorrow. Part of this is solved by knowing the moisture content of the woods you are using. If the moisture content of the lid is a bit high, you can build a bit tight, knowing it will shrink. If a bit low, leave it very slightly loose in fit. It might "pop" later on but not push the sides of the box loose.

This is also a matter of personal taste. One thing in your favor in making small boxes, is that due to the size of the material, you will not have movement to the same degree as is experienced in furniture making with wide panels of wood.

I hope this helps.