Introduction: Mini Indoor Fire Pit for S'mores
This project has been on my mind for a while now and what better time to make it than winter months when bonfires and BBQs are out of question.
S'mores were introduced to my European-self via American movies and I never even thought to make them myself. That is until I met my newest friend, who happens to be a s'more obsessed American. Unfortunately, since he lives in an apartment in London, he's unable to make them himself and he's constantly trying to come up with alternatives. Believe me, there is nothing sadder than watching a grown man trying to heat up marshmallows with a lighter or spreading marshmallow fluff over saltine crackers and topping it with nutella. I finally took it upon myself to make him an indoor fire pit to satisfy his cravings.
# Cement or concrete mix + optional powdered pigments
# Mould - silicone mould, 3D printed mould or DIY homemade mould
If you don't have a 3D printer, use plastic containers you have laying around the house to create a simple mould.
# Mould release - oil based
If you are using DIY plastic mould or 3D printed one, you can use any oil based lubricant on hand- cooking oil, baby oil, Vaseline etc. For professional silicone moulds you will need special release agents to prevent damage.
# Sanding paper, at least 120-320 grit
Optional: Dremel, concrete polishing pads
# Concrete sealer - optional
Only non-solvent sealer! It can be skipped altogether if you absolutely don't want to use it, but it will look better and cement won't be prone to stains or damage.
Sealer can usually only be bought in large quantities, but sometimes you can buy samples (1-2 oz.) on eBay and Amazon.
# Decorative stones or pebbles
# Heat-proof metal container for alcohol burning
# Methanol, ethanol or isopropyl alcohol (rubbing alcohol) - high concentration
I tested 70% and 99% isopropyl alcohol and both worked, however 99% burned longer and more consistently.
# chafing fuel https://www.amazon.co.uk/Olympia-CE241-Chafing-Fue...
Step 1: Moulds
You can buy special silicone moulds or make them yourself using household items like plastic and metal containers, melamine boards or even cardboard.You can also 3D print them.
I've found an interesting bowl design on Thingiverse, I tweaked it a bit and made it into a mould. When I'm no longer using the fire pit I will be able to fill the bowl with decorative pebbles, candles or use it as a succulent planter.
Step 2: 3D Printing Moulds Using CURA's 'MOLD' Mode
Cura has this interesting feature that allows you to print any object in a mould (mold) form. I have no idea what the intended purpose of that mode is, but I use it to print moulds and fill them with cement or plaster. Not all objects can be converted and still be usable, some have to be modified, but it works great for simple designs like bowls, vases, planters.
Once you made or downloaded a design of a bowl or planter, import it into Cura and find 'mold' feature in settings.
Print your mould upside down.
- 0.2 or 0.3 layer height
- 0.4 mm wall thickness
- 0.8 mm bottom and top
- 2-10% infill (depends on the size of the object)
- use raft as build plate adhesion (at least 2 layers), it will also act as a connector between the outer mould shell and the inner part
Step 3: Cement/ Concrete
Use cement or concrete mix, either one will work. While concrete is stronger than just cement, on a small scale project like this the lack of aggregates won't matter as much.
In fact cement works better than concrete, since there are no gravel pieces and the whole mixture fills small cavities perfectly, so the end result is flawless.
Cement doesn't usually stick to PLA too much, so mould release is not strictly necessary, but I like to spray some WD-40 on the insde of the mould just in case.
Mix a batch or cement- white, pale gray or dark gray (whatever is available in your country), add pigments if you want to and pour into the mould.
Bang the whole mould onto the countertop to release any air bubbles and to spread the mixture evenly. Level the top and leave to set.
It should be ready to de-mould within 2-3 days.
Once out of the mould, you should leave it to dry and further cure for 1-3 days.
To de-mould you might use:
- thin flat screwdriver to break the mould
- exacto knife
- sharp wire trimmers
Step 4: Sanding and Sealer
Use sanding paper to smooth the cement bowl. Start with 120 and go all the way to 320 (or higher) for a polished look.
You could also skip the sanding process and keep it rough looking if that's what you like. Or go the other way and, if your bowl is relatively simple, use cement polishing pads to give the bowl a nice shine (https://www.amazon.co.uk/Sanding-Polishing-Grindin...).
Brush one or two thin layers of sealer and let it dry completely.
Step 5: Create a Care Package for a Friend
It would be a nice gift for a s'more obsessed person.
Pack the cement bowl in a box with a bottle of rubbing alcohol, skewers, decorative stones, matches, small metal container, marshmallows, chocolate and crackers.
Step 6: How to Burn Alcohol Safely
1. I know that it's not recommended to burn fire directly in a cement fire pit without any protection. At least that's how it's supposed to be done in large, outdoor fire pits. When exposed to direct, high heat, over time, cement can crack or even explode. Now, in theory, you won't be using this indoor fire pit for hours on end, so the possibility of the cement cracking is low, but... I read about the cement bowls exploding and now I can't put it out of my mind, so for safety, I recommend using a metal container that will fit within the bowl.
2. Have a metal or glass lid on hand, just in case you have to extinguish the fire. Don't leave the fire unattended and put it out even when walking out of the room for a moment. Especially if there is a possibility of a draft.
3. 1TBS of rubbing alcohol will burn between 3 and 5 minutes. Start the fire with small amounts of alcohol, just until you get an idea on how much to use and how long it will burn for.
4. EXTINGUISH THE FLAME BEFORE ADDING MORE ALCOHOL.
Step 7: Finished
Second Prize in the
Winter Fun Challenge
5 months ago
I made a candle at an event and, after realizing how hot it was, I found that lighting candles also work pretty dang well if you are on a budget/don’t have a maker space or something to print this. The only bad thing is that those are finite.
Question 7 months ago
Hi do you know if you could post the 3d printable files
8 months ago
This is a great idea! However, I made an account to say that rubbing alcohol is not safe to cook on, or even burn in an unventilated space. It is isopropyl rather than ethyl (drinking) alcohol, and therefore toxic, especially when burned. It might be really toxic to eat something cooked over it. So I would suggest using everclear, or another type of ethyl alcohol. Please check out this wiki page on isopropyl alcohol to learn more: https://en.wikipedia.org/wiki/Isopropyl_alcohol#Toxicology
11 months ago
Very nice textures!
1 year ago
Hi Kura, you had me laughing with your comments about S'mores and your friend. It was so nice of you to take pity on an American, away from home, and craving S'mores. Did He or she make you some? I hope so. I have an idea that might make using your indoor fire bowl more safe. We have in America a product called "Sterno". It is an alcohol gel like substance used to keep food warm in chafing dishes at buffets. It is food safe and your friend can roast his marshmallows and S'mores over it without worrying if it is toxic. It looks like the can it comes in may fit inside the cement bowl. Your friend should know what it is but just in case I am adding a Google link. OH, forgot to tell you that you can make S'mores in the oven. You can charr the marshmallows with a small blow torch and even a regular one if you wan't. Just be careful with the big torch.
can s'mores be made in the oven
Reply 1 year ago
Sterno has a kind of chemically taste, but it WOULD last a long time! And it can be covered and reused without loss from drying. What about a candle or several?
Question 1 year ago on Step 6
Could you carve a shape into wet sand to form your outside container, then pour concrete into it? Then push a plastic bowl into the concrete to form your interior wall?
Maybe the concrete would mix with the sand too much…
Answer 1 year ago
That would work as well. Mold release the bowl though! And the sand would be a great tactile for the outside surface.
1 year ago
Hi Kura. Nice tips on molding concrete! I’m just starting to experiment with it myself, and in the process, I created a tool to help other makers design 3D print molds. I’d love to get your feedback on it! https://parafab.com/casting-mold/
1 year ago
Nice project! I had not thought of 3D printing a mold for concrete. S'mores are great and this makes it a more accessible treat as some folks don't have space for a campfire. Three thumbs up!
1 year ago
That's great! I'm sure your friend was super happy!
Thanks for sharing :)
Reply 1 year ago
Love this idea. Thank you for sharing.
1 year ago
That looks so nice! And thanks for including some safety tips :)