How to Add Weight to 3D Prints (Fill) – PLA & More


Many people wonder how they can add weight to 3D prints, so they are sturdy and have better durability, but they aren’t sure what the best way to do it is. This article will take you through some techniques that 3D printer hobbyists use to add weight to 3D prints.

Keep on reading through this article to learn how to get this done.

How to Add Weight to 3D Prints

There are three main methods to add weight to 3D prints:

  • Sand
  • Expandable foam
  • Plaster

Let’s go through each method below.

How to Fill 3D Prints With Sand

You should look for sand that has been washed, dried, and cleaned.

The basic idea of using sand as fill material is to make a 3D print with an opening, fill it with sand, and then close it by completing the print.

Things you need:

Here’s how to fill 3D prints with sand:

  • Begin your 3D print
  • Halfway through your model printing, pause it and fill it up with sand
  • Resume the print for it to seal the model up.

Sand infill from 3Dprinting

It’s important to keep in mind that there are fans and electronics on a 3D printer. The fans can actually blow sand around which can be an issue, especially if the sand reaches your electronics. Some electronics are placed underneath the build plate so check for this beforehand.#

You can try to cover the electronics while applying the sand.

One user suggested putting a little water on the sand to make it less likely to blow away. Make sure you protect your eyes with goggles or glasses while applying the sand.

There is a good chance your 3D print will have air gaps since the sand usually won’t be filled up to the brim.

Pros

  • It’s an inexpensive filler
  • Sand that has been washed and dried won’t stain your 3D print.

Cons

  • Won’t fill up the whole space, so there will be air gaps.
  • When you shake a 3D print filled with sand, it always makes a rattling sound because the sand particles are not packed together tightly.
  • Since sand grains aren’t very heavy, the fan in the printer may blow them around. This could affect the way your 3D printer works if the sand gets to its electronics.

Check out the video below to see the process visually.

How to Fill 3D Prints with Expandable Foam

Expandable foam is a good choice for filling larger 3D prints.

One good thing about this foam is that it grows to fill the empty space. It might be hard to use at first, but you’d learn how to do it over time. Because of this, it is a good idea to have a demo to test it before you use it on your real project.

Things you need:

  • A drill
  • Some cans of expandable foam
  • Paper towel to clean up the mess
  • Acetone
  • Plastic putty knife
  • Hand gloves
  • Eyeglasses
  • Long sleeve clothing for safety

Here’s how you fill 3D prints with expandable foam:

  1. Make a hole in your 3D prints with a drill
  2. Fill the 3D print with foam
  3. Cut away extra foam and clean it up

1. Make a Hole in your 3D Print with a Drill

The hole is needed so you can inject the 3D print with foam. It shouldn’t be too large and you need to be careful while drilling so you don’t break the model. You want to drill at a fairly slow pace. Make sure the hole is big enough to fit the nozzle from the expandable foam.

Check out the video below to see how to effectively drill holes in 3D prints.

A simple one like the Avid Power 20V Cordless Drill Set from Amazon should get the job done.

2. Fill the 3D Print with Foam

Now we can fill the 3D print up with foam. It’s a good idea to read the safety instructions of the foam before using it. Use the correct safety equipment such as gloves, safety goggles and wear long sleeve clothing.

Put the straw or nozzle into the hole you drilled then press the trigger of the can to squirt foam into the model. It’s advised to apply pressure slowly and occasionally take the foam container out and shake the can.

Make sure you don’t fill it up all the way because the foam expands during the drying process. I’ve heard you can fill it to about three quarters to get the object to fill.

After that, leave the model to dry but check on it every so often to clean up excess expanding foam.

I’d recommend going with the Great Stuff Pro Gaps & Cracks Insulating Foam from Amazon. It has many positive reviews and was used by Uncle Jessy in the video below with success.

Check out the video below to see how Uncle Jessy adding expanding foam to his 3D print.

3. Cut Away Extra Foam and Clean it Up

The foam may have grown in places you don’t want it to or may have gotten on the surface, so you’d have to do a little cleaning to keep your model looking good.

A solvent can be used to get rid of soft, wet, expanding foam that hasn’t been set yet. In fact, if you try to clean up expanding foam residue that hasn’t set yet with a solution that doesn’t contain a solvent, you might end up setting it instead of cleaning it.

  • Use a plastic putty knife and a dry, soft cloth to remove as much of the leftover expanding foam as you can.
  • Use acetone to wet a second dry cloth
  • Lightly rub the acetone into the expanding foam residue, and then, if necessary, press down on the surface and rub it in a circular motion. Acetone can be used as needed to re-wet the cloth.
  • Wipe away the acetone with a soft cloth that has been dampened with water. Remove all of the leftover expanding foam before you put the water on.

Pros

  • Expands, so it can quickly and easily fill up a big space
  • The foam can’t be squashed, so it gives your 3D print good stiffness

Cons

  • Hard to predict how much the foam will expand
  • If you don’t handle it carefully, it can get messy
  • The foam doesn’t weigh much
  • Not good for filling small 3D prints

How to Fill 3D Prints with Plaster

Plaster is another material you can use to add weight to your 3D prints. I will take you through how you can successfully fill your 3D prints with plaster.

Things you’ll need:

  • A syringe with extra needles or get a few syringes
  • A drill
  • Tissue paper
  • A container with water for mixing plaster
  • A fill and mix tool, like a spoon.

1. Make a Hole in Your 3D Print with a Drill

  • Drill a hole in your 3D model – it should be slightly larger than what you need, usually around 1.2mm

Make sure you use a medium/low drill speed. Some people recommend drilling two holes so one can be used to inject plastic and the other to relieve air pressure.

2. Mix the Plaster with Water to Form a Paste

  • Now you simply create the plaster mixture by adding water to it to form a paste
  • Follow the instructions of your specific plaster, and make enough for the size of your model

Make sure to use a separate container and not put water into the plaster bag. You can add the dry plaster little by little as you stir until it forms a paste, making sure to sir well.

The final form of the mixed plaster should be somewhere between a liquid and a paste, not being too thick since it won’t be able to go through the syringe needle and would dry out quicker.

3. Insert the Paste into the Model

  • Here is where you use the syringe to insert the plaster paste into the model, through the drill hole.
  • Carefully suck the plaster paste through the syringe needle
  • Place the needle through the hole and eject the plaster into the model
  • As you do this, lightly tap the 3D print each syringe release so the plaster can flow evenly and fill the spaces

You can let the plaster spill over from the model to make sure it’s filled correctly, then you wipe off the excess with tissue while it’s still wet. Let the model dry, which can take up to a day depending on how thick the mixture is and how humid the area is.

Taping the hole afterwards is a recommended step to keep the plaster from flowing out.

If your model gets stained during this, you can wipe up the plastic with a damp tissue before it dries. Make sure you clean your syringe needle out so it doesn’t clog up.

For 3D prints that aren’t hollow, you’ll have to drill multiple holes in key spots to let the plaster fill up the spaces in the model.

Check out the video below for more details on this.

Pros

  • Gives the model a good amount of weight
  • Completely fills the object and doesn’t make any noise when shaken.
  • Makes the 3D print feel strong
  • Works best for 3D prints that are small or medium.

Cons

  • Can get messy
  • Care must be taken when using needles
  • Too heavy for big 3D prints, and you would use up a lot of material.

How to Add Weight to Chess Pieces

Have you ever felt that your chess piece is light and would have been better with a little reinforcement while playing? This section is for you. We will show you how to add weight to your chess pieces.

Here are some things you’ll need:

Different pieces have different-sized holes at the bottom, so you can use different-sized weights. For example, since the king’s cavity is bigger than that of the pawn, it would naturally hold more weight.

Add Weight & Filler to Chess Pieces

  • Remove any felt from the bottom of your chess pieces
  • Add some filler to the bottom of the hole to hold the weights in place
  • Add your desired amount of weight to the chess piece while adding more filler to hold it
  • Fill the rest of the chess piece with filler up to the brim
  • Wipe up the edges of the chess piece with a paper towel and stick to make it level
  • Dip a flat stick in water and use it to smooth over the filler
  • Repeat this process for each chess piece.
  • Leave it to dry for a day or two
  • Sand the filler so it’s smooth and level

The video below suggested using lead shots to weight down chess pieces instead. You flip your piece over, fill it with lead shots, put glue on it to hold it in place, and then file it to get rid of any protrusions, so it’s ready to be felted.

Now let’s move on to felting the chess pieces.

Add Felting to the Bottom of the Chess Pieces

  • Get some felt from a fabric store or online
  • Cut out a rough size from the felt that is slightly bigger than the base of the piece.
  • Add lines of PVA glue over the filler and spread it evenly around and on the edges with a toothpick or small piece of wood.
  • Stick the chess piece to the felt that you cut out, pressing it firmly all around
  • Set it aside and give it about an hour to dry
  • Cut the felt with some good scissors, going around the chess piece
  • Continue cutting the edges of the felt so there isn’t any sticking out

Check out the video below to see the whole process.

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