Hot Glue Mosaic Coasters (or Tiles)

These colourful Hot Glue Mosaic Coasters are fun to make. I was looking at lego art, which made me think of iron melt beads and with the hot glue contest in the back of my mind I thought of doing this.

Instead of the cutter, jig and hole punch, you could just use a craft knife and a normal hole punch. I didn't have a hole punch of the right size, so I made one. Your punch might also get a bit gluey.

I made the cutter jig because I wanted the slices to be consistent. I made the cutter because I found it easier to cut the glue sticks with pressure from above.

7mm hot glue sticks in various colours.

Parchment paper

Clothes Iron

A surface to iron on ( used a folded tea towel to protect the surface of my kitchen counter )

Mould release ( I used Silicone spray )

Safety goggles

Dust mask

Gloves

For the mould, cutter and hole punch

3d printer

Filament ( I used PLA and it held up fine, but filament with a higher melting point, like PETG or ABS, would be better for the mould).

Tinkercad and a Tinkercad login.

Small blow torch

Calipers or Ruler

Cutter:

Craft knife with a long blade

Hole Punch:

4mm Aluminium Rivet

Dremel or drill with 2mm, 2.8mm and 3mm metal drill bits.

Sandpaper

Pliers ( I used needle nose pliers and wire cutters )

Hammer

Bench vice (or another way to clamp the rivet while drilling.)

Popsicle sticks

I modeled the mould, hot glue cutter and hole punch in Tinkercad.

I've included instructions for modeling the mould in Tinkercad as I thought you might want to customise it for larger grids or thicker glue sticks. I've also included all the stl files and a link to the Tinkercad file for the mould and tools. I haven't included instructions for modeling the cutter and hole punch. They are both made up of simple boxes and cilinders in Tinkercad. I'm happy to answer any questions regarding the 3D modeling or anything else.

Open Tinkercad and log in. Start a new project.

1: Create the grid

In The shapes panel search for "grid".

Select a shape called "grid of square columns" and enter the setting as follows:

Columns: 10

Rows: 10

Size 7.5 ( The diameter of a glue stick + 0.5mm tolerance. )

Gap: 0.4 ( I wanted the blocks seperated by a very thin line and this is the width of my printing nozzle.)

Height: 3 ( This will be the thickness of the coaster. )

The finished grid should measure 78.6mm x 78.6mm. This will be the size of the coaster.

From the basic shapes menu add box and scale it to 78.6mm x 78.6mm x 2mm.

Click on align and align it to the top of the grid.

2: To make the rounded corners

From the basic shapes menu add a box, make it a hole and set the radius to 1.

Scale the box to 78.6mm (width )x 78.6mm (length) x 20mm (height).

Add another box and scale it to 80mm (width )x 80mm (length) x 10mm (height).

Select both boxes and click on "align". Center the boxes and then group them.

Make this new object a hole.

Centre align this object and the grid and group them.

3: Complete the mould

Add a box and scale it to 83mm x 83mm x 4mm (height).

Align this box and the grid with the rounded corners from the previous step, so that they are centred on the x and y axis.

Align the grid to the top of the new box.

Make the grid a hole.

Group the grid and the box

Select the new object. Click on export and select stl.

I printed the coaster mould in PLA with a layer hight of 0.28 and 25% infill.

Download and print the blade grip and cutting guide stl files. I printed them in PLA with a 0.28mm layer height and 25% infill.

Break a section of three blades off a long craft knife blade. I put the blade in a craft knife and used pliers to break it off.

Insert the section of three blades in the blade grip. If it's a bit loose, either heat the blade with a blow torch before you press it in or add a bit of hot glue to the blade before you press it in. If the fit is too tight, heating the blade will help too.

Place a glue stick in the cutting guide.

Place the blade in the blade slot of the cutting guide and press down.

Download and print the hole punch housing and hole punch guide stl files.

I printed them in PLA with a 0.28mm layer height and 25% infill.

Start by separating the inside and the outside of the rivet. I did this by holding onto the each part with a pair of pliers and pulling them apart a bit to start. Then I held the tube in the needlenose pliers and hit the sharp end of the peg with the hammer. Keep the peg for later.

A drill press would be handy for the next step, but I don't have one.

Put the rivet tube in a vice with the narrow, sharp end facing up.

I put it between popsicle sticks to protect the vice. The metal gets quite hot and I damaged the rubber on my vice a bit on my first try.

Using a 2mm drill bit, carefully and slowly drill about 5mm into the rivet to make the opening larger. Try not to go deeper, as the metal becomes too thin and soft. Do the same with the 2.8mm drill bit and then with the 3mm drill bit, to gradually increase the opening to 3mm. Gradually increasing the side of the drill bit resulted in the neatest cutting edge.

Clean up the edge with sandpaper if it's necessary.

Insert the rivet tube into the hole punch housing.

Heat the tip with the blow torch and put the punch housing in the punch guide, so that the rivet tube goes through the hole in the bottom of the guide.

The heating of the rivet helps secure the rivet in the punch housing and melts the plastic of the punch guide, in case the hole is slightly too small for the rivet.

put the rivet peg through the hole to help align the rivet tube, punch housing and punch guide and let it cool.

I made three coasters. I planned the first one in Adobe Illustrator using coloured circles.

For the second one I just built it directly in the mould.

Because I made the third one out of leftover disks from the first two, I printed out a template of the grid (made in illustrator) and planned it on paper with the leftover disks before I transferred them to the mould.

You could also just draw your designs on paper with markers or coloured pencils.

Keep in mid that the final coaster will be a mirror image of the design you see in the mould. If the robot's looking to the right when you're placing the disks in the mould, it'll be looking to the left on the final coaster. Especially keep this in mind if you're planning to use text as part of your design.

I've included a pdf of the printable grid.

Using the cutter and cutting jig or a craft knife and ruler, cut up some glue sticks.

If you planned your designs, count how many disks you need of each colour. If not, just cut disks of the colours you like. You'll need 100 glue stick disks per coaster.

Put one of the hot glue disks in the hole punch guide.

Put the punch in the guide and press down. Depending on how hard your glue sticks are, this might take a bit of force. For some of the disks I used a hammer to hit the top or bottom of the punch to get the last bit through.

Use the rod you removed from the rivet to remove the hot glue dot from the punch.

Remove the punch from the guide and remove the leftover hot glue disk from around the punch.

You now have a disk with a hole and a dot. Combine dots and disks of different colours by pressing a dot into a holed disk of another colour.

Spray the mould with mould release. I used silicone spray and while I didn't try anything else, I think cooking spray might work too.

Arrange the hot glue disks in the mould. The side facing down is the side you'll see in the end, while the top will be melted. If a disk is a bit rough on the one side, face the better side down.

Do this in a well ventilated area.

Protect your work surface from the iron. I worked on a folded tea towel.

Place the mould with the hot glue design on some parchment paper ( to protect the surface from glue).

Place two more sheets of parchment over the design. The first one will stick to the hot glue while it's melted. The second one will move with the iron and help it to move over the mould smoothly. It also adds another layer of glue protection for the iron.

Test the heat of your iron with a couple of pieces of hot glue between parchment. You want the coolest setting that will melt the hot glue. The plastic mould will hold up better if the iron is cooler.

My iron was set to the Nylon setting and the PLA mould held up fine.

Place the hot iron on the parchment and slowly move it around, checking every few seconds to see if the glue as melted. Just lift off the second layer of parchment to check the glue. If it's sticking to the parchment everywhere and the top looks smooth, you're done ironing. Leave it to cool. It shouldn't take very long to cool.

When the coaster and mould has cooled, peel off the parchment.

If the hot glue stuck to the outside edge of the mould, with the blade or a craft knife, carefully cut around the inside edge of the mould to release the coaster.

Use the same blade to lift a corner and then use your fingers to lift the coaster. Work carefully and from the outside inwards.

Wipe off any mould release with paper towels.

Trim the edges with a pair of scissors.

That's it! Enjoy your coasters and remember to switch off the iron when you're done.