I'm staying near the beach at the moment and was inspired by the junk there and some plastic bag material instructables. My friend and I made this costume for a video shoot. It's a bit makeshift so while it's possible to move around in, it only covers the front making it best for posing on the rocks or in the sea.

You will need
- about 5 different colour plastic bags (sea themed is best so blue, green, purple, gold, silver)
- 5 white or whatever colour bags
- tissue paper/baking paper (not waxed)
- an iron
- scissors or other cutting implements
- an old bra or bikini top
- a pair of old leggings or other stretch material
- needle and thread
- pins
- ghost nets or other sea junk to use for hair
- copper tape or another decorative tape or ribbon (optional)
- leggings to wear with the costume

Step 1: Making the Tail Pt1

The tail is in two pieces so that the mermaid can bend easily at the knees. the top part extends from the hips to below the knees, and the bottom part from the knees to beyond the feet.

We will use the plastic bags to create the tail. Keep all your coloured bag offcuts - we will use them later.

First, flatten the plastic bags, cutting off the handles and the bottom that seals them all together.
This will give you sheets of flat plastic. Put the white/whatever colour bags aside as they will be the back of the costume.

Cut scale shapes out of the colours - you will need about 150 of these (for a shortish adult) You can take a shortcut by folding and layering the plastic bags before you cut them - then you can create loads of scales with just a few snips.

Measure the mermaid! Measure the distance from the hips to the knees, add another 30 cm to that measurement - this is how long the top part of the tail needs to be. Hold the white/whatever plastic bags against the mermaid-to-be and measure the size required to cover their front and sides. It may take two or more bags for this. Cut the plastic to the required size.

Lay out one piece of tissue paper, on this lay flat the white/whatever colour bags, this will be the base for the scales.

Starting at the bottom of the tail, place one line of scales on the background plastic.

Cover with tissue paper and iron on a low heat until the plastic is fused together. Keep the iron moving - you may wish to experiment with this beforehand.

Add the next layer of scales, cover and iron. Keep repeating this until the background plastic is covered with the scales. If you needed more than one piece of background plastic then fuse it to the other piece using the iron.

Step 2: Making the Tail Part 2

(just a note - i don't have photos from the original costume for this step - so I have used a small scale version to illustrate)

Measure the amount of plastic needed for the length of the tail. it should go from the knees to beyond the feet.

Cut two rectangle pieces of plastic for each side of the tail fin. Iron them on to the main piece of the fin so you get a T shape.

Cut the tail shape out from the T.

Now decorate the bottom of the tail using the same technique as before - adding scales. For the tail area you may wish to change the shape of the scale you are using.

Step 3: Making the Tail Part 3 - Finishing Up

To be able to wear this tail we need to add straps.

Cut 8 strips of plastic approximately 10cm x 30cm. The length of these pieces depend on the size of the person wearing the tail. The strips need to be long enough to go around the back of the person and then tie in a knot. If you aren't sure of the size then make them extra long, you can always cut them later.

turn the tail pieces onto their fronts, cover with tissue paper then iron on the straps until they are fused to the costume. Iron 2 straps to each side of each piece of the tail.

We found at this point that the costume looked a little flat so we added some more scales. This time however don't iron the whole scale to the costume. Just attach the top so the rest can flap in the breeze.

Step 4: Making the Bikini Top

The mermaid may wish to go au natural - but if it's a modest mermaid then she may want a bikini top.

Fuse 2 layers of blue bag together enough to use for the decoration on the top of the bikini.
Sew the blue plastic along the top of the bikini/bra - bunch up the plastic as you sew to get a frill effect.

I put some copper tape along the bottom of the blue plastic for a little effect

You should have alot of different coloured scraps of plastic lying around now.
Using this plastic cut uneven strips about 10cm long.
Twist these strips a little and fold them in half.
Sew the top of the fold onto the bikini top.

Start this at the outside top of the bikini and work across. When one row is done start a row below. The rows don't need to be right up next to each other. Some gap will be covered by the above row hanging down.

Keep sewing the plastic on to the bra/bikini until it is all covered.

Step 5: Junk Wig

The wig base
You need a base for the wig. Grab the old leggings

Wear the leggings on your (or the future mermaid's) head by putting your head into the thigh area of the tights. Pull them down so they are tight on the head.
Mark the curve of the head. Mark where the forehead is.
Sew along the line where the curve of the head is marked
cut the tights so the cap fits down to the forehead

The hair
I'm living near a whole heap of sea junk which is what inspired the whole costume. If you don't have access to ghost nets and rope then perhaps shredded plastic bags, old stockings or whatever else you feel suits will work.

You should have a few clumps of ghost nets, sea junk or other hair material. While the future mermaid is wearing the wig base, pin a piece of net into place being careful not to stab them with the pin.

Step 6: Putting It All Together

Congratulations you are now ready to be a mermaid, destined to spend your days lolling around the ocean.

Put your leggings on - we used gold ones as they worked well with the costume if exposed.
Put the bikini top on
Wrap the bottom part of the tail around your legs and tie at the back.
Wrap the upper part of the tail around you and tie at the back.
Put the wig on and you are ready to go!