Cheap material to make master for silicon mold

Projects
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I want to make some master blanks and looking for a good material to carve them out of that isn’t very expensive. Need something 1 inch deep at least. Seen machinable wax or HDPE but those are a little pricey. Going to be making quite a bit of different designs so will need quite a bit, hence the price concern.

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Have you considered melting your own HDPE and cutting into whatever you need?

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Kinda looks like something that’d be suitable for using MDF.

MDF is cheap(ish) and can easily be made thicker by gluing sheets together. It carves well and usually gives a pretty good finish.

Keep in mind the dust isn’t good for you (it’s basically just sawdust glued together and the glue isn’t non-toxic) and it can make a mess without some way of collecting the dust. If you have plenty of patience, but no fitted dust collector, you can stand there and hold a vacuum hose near the bit while it carves to manage this (you may laugh, but I did this for months when I first began…)

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Fuse cheap HDPE sheets together.

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Pink or Blue foam board that you can find at the home stores… machines well, can be glued together to increase thickness. stands up to medium heat… doesn’t break the bank…
but you’ll need to spray the molds with Primer and then mold release if you’re using them as positives for silicone molds.

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good to know, ill look at that, thank you

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Whats the finish like on the carve? Also do you have suggested Feed Rate/Plunge Rate/Depth per Pass numbers for easel

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When I was a kid I would melt down a lot of these, pretty sure it is HDPE. https://www.amazon.com/TimMee-PLASTIC-ARMY-MEN-Soldier/dp/B005LDBCC6

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I use the Linoleum or HDPE settings for cutting Foam Boards.

I saw this video: https://www.youtube.com/watch?v=NBZUDRxwaKA and went with the cheaper route for materials. However if you do require a sturdier Master, consider the fancier options.

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I ended up spending the little extra and going with HDPE so that i can keep the master mold and make more

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I use plaster of Paris for hand-made molds (start with clay to make a plaster cast that you can refine, then make a plaster mold of that). That’ll probably be the cheapest solution, assuming it carves OK with a router (I suspect it will)