Introduction: How to Make a Soup Can Forge

The above video details the process I used to create a simple and inexpensive propane forge from commonly available materials. In the video below this forge is put to use for the first time making a small fixed blade knife.


LETEmDROP (author)2013-05-09

I made one and I love it! This really got me kick started into black smithing, and I am now in an apprenticeship with a friend of mine. Here's a picture of mine. I used a longer can for longer pieces of steel. Ot fires great as long as you have the right blow torch head (spiral flame).

Jessesnowden (author)LETEmDROP2015-10-15

How long has your forge lasted? Any breakdown of the plaster yet?

How long does the propane canister last? I've not used mine for any extended period of time, and i dont keep track of how long I've used it. Could I hook this up to a large propane tank?

Looks awesome!

rmoulden made it! (author)2015-01-23

This thing is awesome for my purposes, thanks for a very useful Instructable! :)

Looks great!

Rory_iow made it! (author)2014-06-07

I made one out of a soup can laying around in my workshop, i then got some plaster and sand thinking it wasn't going to work and was pleasantly surprised when i forged a mild steel L bracket and put it in the N06 Vice and whacked the crap out of it ;)

RSund (author)2017-03-03

How Did you get the flame to get so big?

Fredrey (author)2016-12-15

Would I be able to make a hole in the other end so I could heat longer peices of metal, or would that break the creation?

MARK FORTY TWO (author)2014-05-03

Will this work with a paint can

Actually search up paint can forge and there is a whole different instructable for a paint can forge, because I doubt the same method used here would work for a paint can, only because a single blow torch could not heat that entire space enough to be useful

witherslayer77 (author)2016-06-15

my igniter for my torch does not have a button that stays pressed in when pressed in, and then comes out when pressed again. Is it safe enough to use tape to hold it in place, or should I find a different igniter?

mpantano (author)2015-02-19

Awesome instructable Dude!!! super simple! Hope you can write for me the composition of the plaster (i didn´t understand that part of the video, as english is not my first language) and the type of gas used with the torch. Best regared!

DarthAnimus (author)mpantano2015-07-11

50% plaster of Paris and 50% sand mixed to a thick clay consistency

GerrieP (author)DarthAnimus2016-05-25


uss_albemarle (author)2016-04-12

made one for my shop class to use. Works good. Thanks

RyanRamos98 (author)2016-03-01

Cant get mine to heat

TheNotoriousHoppington (author)2016-01-25

The only sand I could get my hands on was 50 lbs of play sand. After looking at this instructable again, I think I need a different type of sand, or more plaster in the mix. The forge doesn't seem to evenly heat, and the only place I could get any metal to turn red was right in front of the flame. Also, how long does it take to properly cure? Thanks.

jwren3 (author)2016-01-09

on other videos they leave the tunnel the whole way through. would that be better? also why dont you just put a can in the middle while it sets then the hole would look allot cleaner.

MichaelB329 (author)2015-12-22

How long should it take to get to max temperature on first use? Im trying to speed up the plaster/sand mixture drying but its taking a while

Josh Peper made it! (author)2015-10-28

great project. the plaster dryed alot faster then I thought but I think it worked out great I look forward to using it.

Jessesnowden (author)2015-10-15

To the original uploader or anyone who has built this: what is the lifespan of the plaster when forging steel? I am building a forge to make knives and may also be doing some forge welding. Need to know if plaster+sand/perlite will be able to stand up to the heat.

Yonatan24 (author)2015-09-25


roncar (author)2015-09-09

Very well presented and helpful. Thanks

WhattheDuck (author)2015-06-20

I'm looking n to making this, I just have a couple of technical questions. 1. What propane torch do you use? A lot of the ones I have seen seem to be brass ends which would melt well before 2000* F. 2. The 1\2 by 2 inch pipe nipple seems to be $50 to get the same one. Does it have to be black iron? does the general size of it matter?

ArthurD3 (author)2015-06-11

I saw other people's version of this and they all led me back to your instructables. I really like the simplicity and straight forward solution.

I don't have any need to make a forge right now but I will make it sometime in the future. For now I'm taking this idea and going to change it up and make a none toxic high radiant heat gas grill. Basically I'm going to replace most of the innards of an old propane BBQ with cast plaster-sand parts. I'll post pictures when I'm done if you or anyone else is interested.

ToggleSwitch (author)2015-06-03

Will this work with a webbed flame torch?

merleman (author)2015-03-04

im new to this so sorry if this is a dumb question but if turned upright could this also be used to melt aluminum?

DerringerHK (author)merleman2015-05-03

You'd need a crucible (like a steel can inside). With the blowtorch that would be difficult. However, if you replace the blowtorch with a steel pipe for air flow and put firelighters and a bit of charcoal in the bottom it could work as you want it to. It would probably be better to do as I said but with a steel bucket instead of a steel can etc (just make everything bigger).

Found a pretty good vid explaining this. Just search "Mini Forge How To" on YT. By a guy named Grant Thompson.

SparkySolar (author)2015-04-20

I am impressed how simple it is, with your excellent clear explanations

GRATTENDARMODY (author)2015-04-18


Sillycrypt (author)2015-03-19

Great! will be making this little forge asap! does anyone know how much gas you save using this for smaller projects opposed to using one made from an LPG bottle?(like the one made here: )

Absintheheart (author)2015-02-05

Hello! I am thinking of trying to adapt this to make a small metal clay/glass kiln. Do you have any ideas or tips? Thank you so much! I am making this one on Sat. I will let you know how it works!

HammE (author)2014-05-13

Wow! What a great idea!!! I'm 15, and I hope to learn blacksmithing a little and your tutorial for a soup can forge will help me out! I actually have a 15 lb anvil my friend bought for me (because I bought him a t-shirt from my last cruise, he is an awesome friend) so basically it's perfect! Anyway, I know the forge worked, but my grandpa doesn't believe that propane get's hot enough, how hot did it get, and how long did it take to get it to that temperature?

rmoulden (author)HammE2015-01-23

Hello there lad, the heat reaches these temp's due to the plaster of paris/sand mixture holding a lot of residual heat. Therefore, it can be used as a small forge for, say, arrow-heads and knife blades. If you need any further guidance on your build feel free to contact me, Best of luck withyour builds!

Rakadoo Man-Chu (author)2014-05-21

rmoulden (author)Rakadoo Man-Chu2015-01-23

Great job!

halo706 (author)2015-01-18

This thing is amazing! Kicks out some serious heat! It's perfect for knife making.

macniven made it! (author)2015-01-09

Thanks NightHawkinLight, your instructables are fantastic! This worked out quite well, though did not get the heat we expected which might be because of the gas chosen, or perhaps the fireproof cement was not yet full cured. Still, it DID work and it great for forging small objects. As a second step we then built a Folding Chair Charcoal Forge, which I have now uploaded to Instructables:

Very nice! It does look like it just may need a little more dry time. It could be the torch though, which looks like a pencil flame rather than spiral.

Oh you know what, that could be it. I should have uploaded a better picture, I actually used a large MILO tin for it, so not quite soup :). I will try it with a spiral flame, having a little forge around for detail work is fantastic. Keep up the great instructables!

nerd97 (author)2014-09-24

I have really wanted to get into blacksmithing for a while now, but always thought it would be a VERY expensive hobby. Now I see so many cheap DIY forges on instructables. Hand-forged Lily Bell (Trafalgar Law's Sword from One Piece), here I come!!

DallinFTWS (author)2014-08-20

I hope to make a beginner forge like this. If I like it enough, I might get in to Blacksmithing!

allindsay (author)2014-07-08

I have a few suggestions. Quench it in motor oil, used or new doesn't really matter. Some people will use olive or some other high smoke point cooking oil for purity but I find motor oil to work great and cheap, also unlike the cooking oils, it never goes rancid.

Also, heat temper the knife in your oven before making the handle or after but before securing it.

And finally, when creating the bevel and sharpening, don;t let it get too hot, dip it in water or oil often.

Nice work though and cool little forge

EurekaFactory made it! (author)2014-07-03

We had so much fun making this we made a step-by-step photo Instructable about it (feel free to suggest corrections if we missed something or misstated) . Now we're looking at making a little portable custom smithy for it, and have a bunch of different ideas for using it at educational events. Thank you!

griffenjoy1277 (author)2014-05-14

I love blacksmithing, but I still need a forge! Great idea.

griffenjoy1277 (author)2014-05-14

Wow! You are awsome!

tokuta (author)2013-12-31

is it possible to put three cans together and make it long enough to make a katana?

kingwolf44 (author)tokuta2014-03-11

you probably could but you would need 1 blow torch per can.

zawy (author)2014-03-07

I found a forum that says this 50/50 mix of plaster of paris and sand will not insulate heat as well as firebrick which means it also retains heat better than firebrick. These forge people seem to think it will not last long at high temperature. One of the posters explains how to make your own firebrick:

"...go to the local concrete plant and buy a bag of fire clay and a bag of sharp silica sand. 2pts, fire clay - 3pts sand - 1/2 pt portland cement. Add only enough moisture to make it clump in a hard squeezed fist and break clean. If it crumbles it's too dry add a LITTLE water. If it leaves your hand dirty or damp, it's too wet add a LITTLE more dry mix. Once it's the correct moisture RAM it in place with a wooden dowel or mallet."

forum comments on this 50/50 mix:

About This Instructable




Bio: I like turning boring things into awesome things! Usually on video.
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