Things You'll Need
Medium Density Fiberboard (MDF)
Few things will ravage important papers and other valuables more than extended exposure to air. If you have been to museums, for instance, you have no doubt seen the airtight display cases around classic works of art. The way mummies were wrapped and sealed in tombs is also a testament to the preservation power that comes from sealing items in an airtight environment. With a few supplies that are readily available at any home improvement store, you could build your own airtight box in just minutes.
Measure the size of the item(s) you wish to place in the airtight box.
Measure sections of MDF for your box. Add room beyond the measurements of the item you wish to store. For instance, if you are trying to secure a stack of papers that measure 8 1/2 inches by 11 inches by 3 inches, then you will want to measure your MDF for a box that is 11 inches by 13 inches by 5 inches to make your box accommodating.
Nail the sides of the box together. Place the assembled sides on the table so that the opening is on top.
Place the board that forms the bottom on top of the sides you have assembled and hammer it in place. Flip the box over so that you have a box with no top.
Apply silicone sealant to the inside of the box along every joint where the wood meets. Allow it to dry.
Place your item(s) inside the box.
Apply silicone sealer along the rim of the box, then nail down the top of the box.
Wipe away any silicone that has been squeezed from the joint during the final steps.
You can make a plastic box very similar to this, using glue instead of nails to hold the pieces together.
Use caution when working with power saws.
Silicone sealant is very adhesive. Apply with care to avoid skin contact. Wear gloves when working with silicone.