Microscopes, precision machines, test equipment, and other sensitive devices should be protected from dust and other environmental contaminants. Use this Instructable to make a decent-looking protective cover from a large tortilla chip bag. The cover can easily be made to fit many kinds of equipment.

Required Materials
plastic tortilla chip bag (or similar)
duct tape
needle and thread

Tools and Supplies
cutting mat
straight edge
hobby knife
jar of warm water
PTFE-based lubricant
solvent-resistant rubber gloves
safety goggles
sewing machine (optional)

Step 1: Prepare a Suitable Bag

Technically, any plastic bag of the right size would work. However, the large bags used to contain a two-pack of tortilla chips as sold by Sam's Club is ideal. They are large enough for many applications, are not contaminated by tortilla chip residue (since they hold bags of chips and not the chips themselves), and are free of all markings except a single removable label.

(a) If the bag contained chips, wash the inside of it with soapy water, rinse, and let dry.

CAUTION: Use appropriate chemical resistant gloves and safety goggles when using solvents.

(b) Remove any labels from the bag (unless you like the way the labels look). One method that works is to soak the label in a jar of warm water for 10-30 minutes. This removes the paper part of the label, leaving (probably) the insoluble glue backing. Use a non-polar solvent such as a polytetrafluoroethylene (PTFE)-based lubricant (Slick 50 works well) to dissolve and wipe away the remaining adhesive. If you have another method for removing glue from plastic without destroying it, by all means, use it.

(c) Alternatively, a preexisting sticker or printed on label can be covered with another sticker of your choosing.

Step 2: Cut the Bag to Size

(a) Place the bag over the device to be covered (in this example, a microscope) to check the fit. There should be 2-5 cm (1-2 in) of clearance between the top of the device and the inside of the bag.

(b) If necessary, trim material off the open end of the bag to achieve the desired clearance at the top. Make sure the cut is parallel to the bottom of the bag or else the cover will fit lopsided and that doesn't look good.

Step 3: Add Decorative Reinforcement

Is it an instrument cover already? Sure, but your instrument will look like it has a tortilla bag thrown over it. A little trim around the open end makes a difference.

(a) Cut a piece of duct tape about 20-30 cm (10-15 in) long and place it adhesive-side down on a suitable cutting surface. A rubber cutting mat works well, especially one with a grid. If you are using a mat with a grid, align the piece of duct tape with the grid so a center-line (lengthwise) is easily visualized.

(b) Trim the ends of the tape segment square using a straightedge and a hobby knife.

(c) Use the cutting mat grid as guide (or measure and mark the longitudinal center-line of the tape) and use a straightedge and hobby knife to cut the tape in half lengthwise. You will now have 2 pieces of duct tape about 20-30 cm long and about 2 cm wide.

(d) Carefully attach one of the tape segments long the edge of the open end of the bag, leaving half of the tape attached and half of it exposed.

CAUTION: Be gentle when installing the duct tape trim to avoid tearing the plastic bag.

(e) Fold the exposed part of the tape over and align it with the attached side so as little of the adhesive side is showing as possible.

(f) Grip the folded over tape between fingers and thumbs and push and roll it as needed to align the two edges of the tape as well as possible. You can correct small mismatches of the edges this way to make it look as good as possible.

(g) Repeat the above steps, starting by attaching the next piece of tape with about a 1 cm (0.5 in) overlap on the end of the existing piece. It takes about three pieces of tape to go all the way around the open end of the bag.

Step 4: Stitch Bind the Trim

The duct tape will eventually work loose if left as is, so to finish the job properly (and to add a more professional appearance) keep it in place with stitches.

(a) Hand sew a seam around the duct tape trim using a simple straight stitch.

(b) Alternatively, use a sewing machine to stitch the seam. In either case, the seam should be close to the open edge of the folded over tape, NOT the folded over edge. Machine sewing this material combination is tricky, but is aided by sewing through thin white tissue paper placed on either side of the part to be sewn. The tissue paper tears away easily afterward.

Note: Use thread the same color as the duct tape to minimize its visibility or use a complementary color to show it off.

(c) For extra durability, sew another binding close to the folded over edge of the duct tape.

Now go about life in the lab assured that your microscope is protected from all the assorted crud that it would otherwise be exposed to.

Acknowledgment : Thanks to Caroline Barton for assistance with the machine sewing operation.