Afaik the putty is a replacement for lead in fishing applications, it has a similar density to lead (putty about 10g/c², lead 11.35g/c²). At that point I'd just use old school lead, you could make a mold for it to pour the required dimensions. Sand should work, you imprint the shape you need and pour the lead in.
A kilogram of lead costs like 5 bucks or so.
Afaik the putty is a replacement for lead in fishing applications, it has a similar density to lead (putty about 10g/c², lead 11.35g/c²). At that point I'd just use old school lead, you could make a mold for it to pour the required dimensions. Sand should work, you imprint the shape you need and pour the lead in.
A kilogram of lead costs like 5 bucks or so.
The problem is that they have inconsistent inner spaces. I would have to make a mold for each individual piece. I also don't have the materials to make molds and melt lead. This sounds like such a big time investment as well as having to get various materials that it makes more sense to just buy more tungsten putty.
You just need sand and normal putty (or really anything that can take an approximate imprint of the inner workings of your piece). Then you flatten a bit of sand, press your shape into it and pour the lead. Lead doesn't need very hot temperatures to melt, even a candle can do it (or an alcohol/gel burner). The only other thing required is a small pan/ladle for heating and pouring, I'd use something like a cheap sauce ladle.
Lead pouring is a common German passtime for kids around new year's so it's relatively simple and not dangerous.
Disclaimer: I've never tried this, but it seems like it should work.
You can get a 2lb bag of 2.4mm lead shot on Amazon for about US$20. If I did my math right, each pellet is about 0.08g. You can fill whatever cavities the pieces have with the small lead shot and then pour in glue/epoxy/resin to fill the gaps. But there might be issues if the binding substance expands or contracts as it sets.
Yeah small spheres would also work (but have a bit less density due to air gaps), tho I'd recommend a less reactive filler like silicone (the one you use in the bathroom to fill gaps). Resin can get pretty hot while curing, not sure the wood would like that.
Number 8 lead shot is 2.3mm so it's a nice size to use for weight. Lead is heavier than Tungsten, but Tungsten is denser than lead, so there is more weight in the same size of tungsten than lead. Here's a quote "tungsten comes out to be 1.7 times denser than lead and around 2.5 times denser than steel. The density of lead is 0.410 lb/in3, which means a cube of lead one inch on all sides weighs 0.41 pounds. Tungsten has a density of 0.70 lbs/in3. So to put it simply, a small cube of tungsten one inch on all sides would weigh 0.70 lbs, or 1.74 times more than the same sized cube of lead." from https://nakoshop.com/blogs/news/lead-vs-tungsten?srsltid=AfmBOopflzRcXVAiGIaTuPLcZIZhyEQaK3hK68e7pB_DImJuKAJq6OWN
Thanks, everyone! I couldn’t find #7 lead shot on the Canadian Amazon, but they had #8, which is 2.4mm. The density of lead shot seems to be 1.35 g/cm3 greater than tungsten putty, and for C$35.40 I got 2 lb (32 ounces) as opposed to C$30.56 for just 3 ounces of tungsten putty.
I honestly don’t want to bother with resin or silicone, and their density will be lower, so I’m placing another order for 3 ounces of tungsten putty, and mixing in the lead shot. That way I will have a higher-density mix than tungsten putty alone (or indeed lead shot with silicone), it’s going to be WAY cheaper (though admittedly not as cheap as lead shot + silicone would be), and the lead shot will stay in place all the same rather than rattle inside the chess pieces.
Smart idea 
, it'll still be far cheaper than the "pure" tungsten putty.
You can get the lead shot in even smaller grain. I used lead granulate with a grain size of ~1mm which I mixed with a bit of sawdust from drilling the holes in my wooden pieces and glue, thus creating a lead putty. No gaps, no rattling and very easy to prepare.
If you check this link and scroll down on the page, you can see it. It was my first try, but I successfully used it several times already.
Modeling clay cost me 1 euro for a packet , Way better than tungsten putty as it cost way too much to do just one set , Used it to weight my chessnut air mod chess set .
You can get the lead shot in even smaller grain. I used lead granulate with a grain size of ~1mm which I mixed with a bit of sawdust from drilling the holes in my wooden pieces and glue, thus creating a lead putty. No gaps, no rattling and very easy to prepare.
If you check this link and scroll down on the page, you can see it. It was my first try, but I successfully used it several times already.
Nice! I couldn’t find it on the Canadian Amazon, and I looked for other stores just now, and didn’t find anything either—at least not for less than what I paid now.
However, I just found powdered lead for weighing golf clubs—1 lb for just $17.25! I will definitely get that next time.
Impressive total weight of your set, by the way! Did you weigh it before you added weight? I’m curious how much weight you managed to add.
Nice! I couldn’t find it on the Canadian Amazon, and I looked for other stores just now, and didn’t find anything either—at least not for less than what I paid now.
However, I just found powdered lead for weighing golf clubs—1 lb for just $17.25! I will definitely get that next time.
Impressive total weight of your set, by the way! Did you weigh it before you added weight? I’m curious how much weight you managed to add.
Be careful with powdered lead, though. There's no safe level of exposure to lead.
As for your question, unfortunately I did not weigh the set before, but since I have several sets of similar dimensions, it is safe to say that the weight should have been around 1.1 - 1.2 kg. So I managed to add some 50% weight by adding my lead compound.
Nice! I couldn’t find it on the Canadian Amazon, and I looked for other stores just now, and didn’t find anything either—at least not for less than what I paid now.
However, I just found powdered lead for weighing golf clubs—1 lb for just $17.25! I will definitely get that next time.
Impressive total weight of your set, by the way! Did you weigh it before you added weight? I’m curious how much weight you managed to add.
Be careful with powdered lead, though. There's no safe level of exposure to lead.
As for your question, unfortunately I did not weigh the set before, but since I have several sets of similar dimensions, it is safe to say that the weight should have been around 1.1 - 1.2 kg. So I managed to add some 50% weight by adding my lead compound.
Nice! Super comparable to what I managed; I added 52% to my Shkolnik II using tungsten putty. I suspect I can get a greater increase with my Shkolnik III by using more lead shot, since its density is higher than tungsten putty.
Thanks for the warning! I figured I could just mix it in with putty, but I think the product description of the powdered lead implies you pour it into your golf club straight from the bottle. Sounds like I should rather avoid using it for my purpose.
I mean, Chuck mentioned using lead powder for golf clubs to add weight to one of his sets, but I’m quite sure he didn’t mix it into another medium and risk greater direct exposure.
Try Modeling clay mixed with lead shots ? 
Try Modeling clay mixed with lead shots ?
I think that’s a good method.
I have been adding weight to my Shkolnik III today, and I found mixing the lead shot with tungsten putty to be impractical. Instead, I fill the pieces with lead shot almost up to the rim, and then use a bit of tungsten putty to cover the opening.
I guess tungsten putty that way adds more weight than modeling clay would, but it’s also a bit unnecessary.
I have added weight to 6 out of 8 of the major black pieces so far, and I already managed to increase the weight of the set by 38%. At this rate, I will end up with close to 100% additional weight I think, as opposed to the 52% I got with the Shkolnik II.
So yeah, the lead shot is already adding a lot more weight than I could with just tungsten putty.
TL;DR: I have used tungsten putty to add weight to my set, which was quite expensive. Is there a cheaper way to add as much or even more weight to a set? I don’t know if putty is even a good medium. Can I get a purer tungsten material?
Added weight
I have a few Soviet carbolite chess sets, and although carbolite is unusually heavy for a plastic, I figured the sets would feel nicer with more weight. I just finished weighting the first set using tungsten putty, and managed to increase the total weight of the set by 52.65%—going from an initial 431.58 g to an impressive (I think) 658.8 g. Not bad for a plastic set!
Cost
The problem is, I spent quite a lot on tungsten putty to add that much weight to the whole set; I spent C$28.19 per 2 ounces (57 g), ordering 4 ounces at first, before I found a cheaper one for C$30.56 per 3 ounces (85 g). I used 52 g of the last batch to complete the whole set; so that’s a total of C$67.88 for one set!
I understand tungsten is expensive, but this second set is very similar to the first one but weighs about 40 g less to start with, so I’m expecting it has larger spaces to fill, meaning I would need even more putty for the second set. I don’t want to spend that much!
Anticipated extra cost
I just finished weighting the king of the second set, which became 2.04% heavier than the king of the first set (though it was 1.23% heavier to start with to be fair).
But the black pawns of the first set had no holes to fill, while the pawns of the second set all seem to have holes. I added about 5 g per pawn in the first set; so for the second set, I will probably need an additional 40 g of tungsten putty for the pawns alone.
This means I will probably end up having to buy an additional pack of tungsten putty for the second set, so that’s an additional C$30.56. At that cost it just becomes an unreasonable project, I think.
Cheaper alternatives?
Is there a cheaper way to add tungsten to my set? Or to add weight using a material that comes close to tungsten?
I also think that putty is a poor medium; it’s easy to use, but I imagine it brings down the total weight. I think I could add a lot more weight if I wanted to by using a different material. I’m looking for a cheaper material with at least the same weight, rather than a heavier material per se; but maybe a different material in a different medium will get me the same weight at a lower cost.
Tungsten powder + different medium
If I were to optimize for weight, I found tungsten powder on Amazon for C$166 for 1 lb (about 453 g). That would have cost me C$79.11 to add the 215.38 g I added to the first set, but with a lot of space left inside the pieces that I could fill in principle.
I guess depending on the medium I use and how much of it, I could easily bring the cost down to below the C$68 I did spend, but I’m not prepared to pay C$166+ all at once; it would make my wife quite unhappy.
Is there a tungsten-weighted medium that is ready to use for less money than tungsten putty? Or are there places where I can get tungsten putty at a lower price than what I found on Amazon? Or a different metal and medium that ends up weighing the same as tungsten putty but at a lower cost?