How to Make an Airtight Plastic Box

Written by donna armstrong
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How to Make an Airtight Plastic Box
The corners of this box can also be reinforced with plastic trim if needed. (blank box image by max blain from

Airtight boxes can prevent some collectibles from becoming dingy or deteriorating over time. These boxes can be used to display treasures or just store them away. Display cases and airtight storage boxes are expensive if you have a vast collection. Making your own boxes will save you money.

Skill level:

Things you need

  • Tape measure
  • Plastic sheets
  • Marker
  • Carpentry square
  • Razor blade or box cutter
  • Towel
  • Window cleaner
  • Super glue
  • Silicone
  • Caulking gun

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  1. 1

    Measure the item that is going into the box. Add 2 inches to the height and 3 inches to the width and length. For example, if your item is 6 inches tall, 5 inches wide and 7 inches long, your adjusted measurements would be 8 inches tall, 8 inches wide and 10 inches long.

  2. 2

    Lay the plastic sheets on a flat surface. Use the measurements to mark the sides and bottom of the box. Use the carpenter's square to make sure the corners are exact. With the example from step 1, two rectangles are drawn for the bottom and top of the box that are 8 inches wide and 10 inches long, two sides are drawn that are 8 inches wide and 10 inches long, as well as two end pieces that are 8 inches wide and 8 inches tall. If the item is going to be removed on occasion, a wooden bottom piece should be created with a groove that the plastic sides and ends will side into.

  3. 3

    Cut out the pieces that you have drawn. Score the plastic with the razor blade or knife on the lines drawn. Turn the plastic over and score it on the back. Continue scoring until it can be bent slightly and can be popped out. Clean the plastic with the towel and window cleaner to remove any marks you may have left.

  4. 4

    Lay the plastic sheet you cut as the bottom on a flat surface. If you are making a wooden bottom, start with the top piece. Apply a small line of super glue to the edge of the flat piece and place one of the side pieces flush with the edge of the flat piece. The two pieces make an L shape. Hold the pieces in place until the glue dries. Then apply a thin line of silicone along the inside edge with a caulking gun.

  5. 5

    Connect the other side and end pieces in the same manner as step 4, applying super glue and silicone on each piece. Do not put on the top piece yet.

  6. 6

    Cover all the corners of the box, from top to bottom, with a layer of silicone. If the box will be moved around frequently, super glue can be applied to the sides of the box for extra strength before the silicone is applied. If you have a wooden base, your box is made.

  7. 7

    Place the item you cherish into the box and apply super glue along the edges of the sides and end pieces. Press the top on the box and apply a thin coat of silicone around the edges.

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