Shrink plastic is one of those supplies that instantly brings back childhood memories, but it is also incredibly useful for grown-up projects. If you want a fun way to make Advent calendar numbers, gift tags, zipper pulls, or personalized charms, shrink plastic is such a good option.
The trick is figuring out how much your shrink plastic will shrink so you can make your pieces the right size from the start. Once you do that, the whole process gets easy and honestly kind of addictive.
Step 1: Decide what you want your shrink plastic piece to become
Before cutting anything, think about the end use. In this project, the goal is to make little numbered pieces for an Advent calendar, but the exact same method works for all kinds of things.
- Advent calendar numbers for sewn pockets or fabric panels
- Personalized charms for wristlets, bags, or zipper tabs
- Gift embellishments that feel handmade and special
- Keepsake projects using a child’s handwriting or drawing
That last one is especially sweet. If a child writes the numbers or draws a little design on shrink plastic, you preserve that handwriting in a durable tiny charm. It turns a simple holiday craft into something much more personal.
Step 2: Make a shrink plastic ruler first
If you do only one prep step before using shrink plastic, make it this one.
A simple ruler made from the same shrink plastic lets you test how much that specific brand and color shrinks. Since shrink plastic can vary, this gives you a custom reference you can use for future projects instead of guessing.
How to make it:
- Cut a strip of shrink plastic.
- Use a regular ruler to measure out 6 inches.
- Mark the inch lines with a thick black permanent marker.
- Mark the half-inch lines a little shorter.
- Mark the quarter-inch lines with a thinner marker.
- Cut the strip at the 6-inch mark.
- Label the inch numbers, including a zero at the beginning.
Use craft scissors, not your fabric scissors. And keep the scraps. Small leftover bits of shrink plastic are still useful for testing sizes, making tiny tags, or creating little accent charms later.
Step 3: Shrink the ruler so you know your actual scale
Once your test ruler is marked, shrink it with heat. A heat gun works well here, though some shrink plastic can also be baked in the oven. Always follow manufacturer instructions and be safe as the plastic gets very hot to the touch.
As the heat hits the plastic, it will curl, buckle, and look dramatic for a moment. That is normal. Keep heating until it flattens back out.
This finished ruler becomes your cheat sheet. From now on, you can compare your planned starting size to the finished size after shrinking.
Step 4: Use the ruler to choose the right starting size
This is where shrink plastic gets really practical.
For example, a charm made from a 1.5″ circle may end up smaller than you want. If you compare it against your shrunk ruler, you can see how large the finished piece actually becomes. Then you can work backward.
If you want the final charm to be about a certain size, use your custom ruler to estimate the starting size before shrinking. In this project, a 2″ inch” square turned out to be a great size for an Advent calendar number.
This step saves a lot of trial and error, especially if you are making a full set of numbers and want everything to feel consistent.
Step 5: Test your shrink plastic because brands can behave differently
Not all shrink plastic shrinks the same way.
Different brands can give you different results. Even different colors or finishes can behave a little differently. Clear shrink plastic and white shrink plastic may not reduce at exactly the same rate, and the finished look can also change depending on opacity.
That means one of the smartest things you can do is run a quick test before making anything you care about.
Even if the project is simple, it helps to know:
- How much your shrink plastic shrinks
- Whether it stays evenly shaped
- How bold your marker lines look after heating
- Whether the color or finish affects visibility
A tiny test square now is much better than remaking a whole set later.
Step 6: Cut your shrink plastic piece to size
For the Advent calendar sample, start with a 2 inch square.
Lightly mark your cut lines in pencil if needed so you do not leave unwanted color on the edges. Then trim the piece down with scissors.
If your design needs a hanging hole, punch that hole before shrinking. It is much easier to do while the plastic is still full size.
Center the hole as best you can, especially if you plan to tie the number onto a pocket or attach it as a charm.
Step 7: Draw the design with permanent markers
Permanent markers are perfect for decorating shrink plastic. For this holiday version, red and green keep everything coordinated with the Advent calendar fabric.
To make the sample number:
- Write the number on the plastic, in this case 14.
- Make the number large enough to fill the space nicely.
- Add a simple border, like dashed lines, for extra detail.
If freehand lettering is not your thing, clear shrink plastic makes tracing easy. Print a number or design, place it underneath, and trace right over it.
And if you are doing this with kids, their own handwriting is the best design of all. Those little imperfect numbers become the whole charm of the project.
Step 8: Set up a safe shrinking station
Before heating your shrink plastic, set up a surface that can handle the heat.
A practical setup is:
- A cookie sheet or metal tray
- An ironing board or other protected surface underneath
- A wood frame to help keep the plastic from scooting all over
- A flat wood block nearby in case you need to press the piece flatter at the end
The wood frame is a smart little trick. Since shrink plastic tends to move around while heating, the frame helps contain it so you are not chasing it across the tray.
Step 9: Heat the shrink plastic until it curls, shrinks, and flattens
Now for the fun part.
Apply heat with a heat gun and keep it moving. The shrink plastic will first curl up and twist. That can look alarming the first time, but keep going. As it finishes shrinking, it will flatten back out.
If the piece is mostly flat but not perfectly square or smooth, press it gently while it is still hot. A flat wood block works well for this.
One thing to remember: if you press with the writing side facing up against wood, a little bit of the marker may transfer. Usually that is not a huge problem, but it is worth knowing ahead of time. If the plastic sticks slightly because it is hot, just flick it off once it cools enough.
Step 10: Compare the finished piece to your shrink plastic ruler
After shrinking, check the size against your custom ruler.
That 2 inch square test piece ends up matching the 2 inch reference on the shrunk ruler, which confirms the ruler is doing exactly what it should. Now you have a repeatable way to size future numbers or charms without guessing.
This is the point where shrink plastic starts feeling really predictable instead of random.
Step 11: Add the shrink plastic number to your Advent calendar
Once the number is finished, attach it to the Advent calendar pocket.
For this style, embroidery floss works beautifully. Thread it through the hole and tie it on with a bow. Red floss looks especially cute against green fabric pockets and ties the holiday colors together.
The finished number is small, neat, and handmade in the best way. It gives the calendar a custom detail that feels much more special than something store-bought.
Step 12: Use the same shrink plastic method for personalized charms
This same process is not limited to Advent calendar numbers.
A smaller starting size, like 1.5″ inches”, works really well for custom charms. Add them to:
- Wristlets
- Zipper pulls
- Teacher gifts
- Handmade bags
- Sewn accessories
One of my favorite ideas is adding a child-drawn shrink plastic charm to a handmade gift for a teacher. It is unique, personal, and impossible to duplicate exactly.
Step 13: Keep experimenting with shrink plastic
Once you start using shrink plastic again, it is hard not to get hooked. It is simple, nostalgic, and surprisingly versatile.
The biggest takeaway is this: make yourself a shrink plastic ruler first. That one step makes the rest of the project easier, whether you are making Advent calendar numbers, personalized charms, or tiny holiday embellishments.
If you want your shrink plastic projects to turn out the size you actually intended, testing first is everything.
And if kids are involved, even better. Shrink plastic is one of those crafts that is genuinely fun, but it also creates keepsakes you will want to hang onto.
