Decisions, decisions

Okay, I have a bit of a conundrum. As I've mentioned before, I'm getting into this whole Geocaching craze (okay, that's a slight exaggeration since this hobby / game started twenty years ago and there aren't that many active players at the moment). Part of the appeal for me is a chance to flex my creative muscles and make stuff.

The reason for this is that part of the game is "swag" (Stuff We All Get), which is basically little trinkets that people leave in the caches so that other players can swap around (a bit like "take a penny, leave a penny" setups). The idea is players put in things they think are worth something and other players can swap them out for things they think are of roughly equal value. Of course, not everybody is going to put the same value on something as another person - but we'll ignore human psychology for the moment.

For me, I don't plan on taking any swag, and I don't have the funds to go buying a bunch of stuff to drop off and give away (as much as I would like to).

So I'd prefer to custom make little thingies. At the moment the main thing I'm looking at is "coins". Not money, some custom made little things that I can keep updating and changing the design on (such as putting the current month and year on them so if other people find them, they can see how long it's been in play).

At the moment my main priority is cost. And I'm looking at six different options.

1. I can print out stickers at home and put them onto little plastic tokens or poker chips. I'm pretty much already set up for this and have produced a couple. I need to refine my process, but it's the cheapest option.
2. Etching aluminium stock. This I've mentioned in prior posts, and I'm sort of set up for it. My results so far have been pretty poor, but I think I may have found a solution. I've ordered some dry photosensitive film, so now waiting for that to arrive. It is the cheap Chinese stuff, so not sure how well it'll turn out, I'll have a play with it when it arrives and hopefully get something better than I'm getting now. If it works as intended, I should see some halfway decent results.
3. 3D printing. If I had a 3D printer, this would be the "ideal" solution, because I could just keep updating the design each month, and make relatively intricate models. The downside is that any machine I can realistically afford will not print the level of detail that I want.
4. Epoxy Resin. This would give a great level of details, but the epoxy is pretty danged expensive. I'd need to start with a 3D printed master, but there is a new re-usable resin available. It works by heating and pouring, so that after spending a month making that version of my thingy, the mould can be melted down and re-used. So the set up costs are low, the mould costs are low, but the resin is around $90 for 250mL.
5. Pewter casting. The great thing about pewter casting is that since it is relatively low temperature metal, I can get away with bodging together some rather cheap tools to get up and running. I've already priced up all the things that I'd need, and it totals out between $100 to $150 depending on sales and how patient I am. The down side is that in order to make moulds, I'd also need a 3D master, and the choices for mould materials are either plaster (low detail level) or silicone rubber (moulds are permanent). The cost of the mould making material is about $100 per 1L, and making new moulds each month could get expensive. Also, pewter is available in cheap (50% lead) and not-cheap (lead free). If costs is my main priority (which is is) then lead is the answer, but if I'm going to be making stuff to put out there that can possibly be handled by kids, then it would be irresponsible to use lead, even if I painted it. Lead pewter is about $25/kg plus postage, and lead free is about $60/kg.
6. And finally, aluminium casting. Possibly give the best results, and has the cheapest material costs (we already collect aluminium cans, so it'd be cheaper to let me melt them down rather than collecting the 10c each and then buying raw material). However, the set up costs are quite steep, over $400 at a bare minimum (and cutting a few corners on safety - not a good idea!) Good for low production runs, because if I 3D print my master, I can use it to make a bunch of sand moulds, then do one large pour and do a bunch of coins at once. Fairly low cost per coin and no chemicals in the house like with epoxy resin … but it has that steep initial cost.

So, not quite sure which way to jump. And odds are, whichever technique I try first, I'll need to stick with that system because I won't be able to afford to switch to another. I just need to make sure I focus on my priorities:

• Affordable: my income goes towards the house, there isn't a lot left over for my interests.
• Safe: I can't have my chemicals or flammable materials injuring myself, my family or any animals.
• Adaptability: I'd rather not keep cranking out the same thingy all the time, I want them to be different from month to month.

Having said that, I did send an email of enquiry to a Taiwanese engineering firm to see how much it would cost for them to produce a steel mould for me. If I wanted to do aluminium casting, then I can't make moulds out of silicone rubber or plaster due to the heat, and sand leaves a grainy texture that needs to be machined to make it look good. A steel mould gives brilliant results - if you can afford to get one made!

Also, I want to build gadget caches, but that's a whole Pandora's box I don't want to open just yet...

Second attempt at salt etching

Curses! I thought I might have been getting a decent result. But, I'm getting ahead of myself.

Current biggest issue is getting a decent resistor onto the aluminium with enough detail that I can get crisp lettering. I think at the moment the issue is that the printer that I have is either low on toner, does not deposit enough toner or is set up to maximise toner and I can't turn it off.

So the first thing I tried was the first method (glossy magazine paper) with a bit of nail polish remover. I also added pressure by using a clamp I picked up from the hardware store. However, I feel that my mistake on this attempt was that I used two bits of metal (the aluminium stock and bit of scrap steel) and it didn't put equal pressure across the toner.

Result: toner didn't stick.

(Also, didn't clean up the metal first either, which can't have helped.)

Second attempt today was using the second method (back of sticker paper - waxy type). This is the one that is supposed to give the best results. The immediate issue was that the toner didn't stick to it going through the printer. Not what I was expecting, I poked around the settings a bit and managed to get a bit of toner onto the paper. The result was … lacklustre.

So I went back to the first method, but this time I put some padding paper between the paper carrying the toner and the steel sheet, and this time I managed to (finally!) get a decent amount of toner onto the aluminium. Yes!

So hooked it all up, got the juice flowing and the result was … about the same as the first time.

It's definitely an issue with the toner. It isn't on there thick enough to stop the salt water from eating away at the aluminium, which leaves it with that chewed out look and rough lettering. I can't think of any other way to get the amount of detail on there that I am after other than printing it. I was looking at the photoresist film, which could work. But that would require buying the film, plus some UV light(s) and who knows how much more equipment. I know we need to buy more toner for our printer, but there should be plenty of black.

I think for the next effort, I'm going to have to try a heat option. Which will either mean investing in a hot air gun or using the oven. Toner should need about 100c to melt the toner, the trick is to not burn it. More experimentation needed!