Just want to say I have over 2 years of experience with those smaller Plano double side boxes. Used the "small size" for 2 years with my TRD finess and on the other side I stacked texas jigs (sinking plastic). Nothing happened, nothing. (see the first 2 picture of that smaller box with scrapers. It has been in a backpack with weather from +30 to -30c (Im swedish) over 1000 times, still good.) Using 3700 for stacking/bulk at home, always those double sides (hard duty!) when fishing around city inshore Stockholm. Last picture are from my new replacement with that 3500 size, love it! Dont get scared of wasting those plastic bags, just remember not to mix em.
Can't edit, the new one is the "medium size" double side plano. Good luck