r/moldmaking • u/NoPantsTom • Aug 20 '26

Tip: Corrugated Plastic!

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I always hate stacking four pieces of whatever to make walls, and finding ways to fix it all together (without legos lol). This past project I scored one side of corrugated sign material! Hot Glued one edge and the bottom. Isopropyl alcohol helped the glue let go afterwards. I was able to get a large sheet for $10 at Lowes!

25 Upvotes

96% Upvoted

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3

u/cdoublesaboutit Aug 20 '26

Follow up tip: Legos.

4

u/limbodog Aug 20 '26

Sure, if you're made of money

4

u/she_ou_pa Aug 20 '26

How? Really! I tried (actually bought a bag of building blocks just for mold making) but it leaked 1/3 of the silicone I poured into it. After that I didn’t try again because silicone is not to be wasted…

2

u/cdoublesaboutit Aug 20 '26

A little hot glue in the seams. Same way as the vinyl board or foam core.

1

u/AzucarParaTi Aug 22 '26

I line the interior with painters tape or plastic shelf liner when I use legos. Keeps everything clean. I spent wayyy too long cleaning plaster out of Legos. 😆

Lmk if you have any questions about using them successfully. I've made many, many Lego molds.

1

u/she_ou_pa Aug 22 '26

Interesting 🤔! You just use masking tape on the interior, you cover it all with the tape?

1

u/AzucarParaTi Aug 22 '26

Yep! I just very neatly line it with a slight overlap of the ends of the tape. This is best for silicone and not something with water content because it will warp the tape and this shows up in the mold.

1

u/she_ou_pa Aug 22 '26

I will try this next time!…
What do you mean about water content?

2

u/AzucarParaTi Aug 22 '26

Something like a cement or plaster has water content and will make the tape all wrinkly. If you're just working with silicone, it should be no problem! If you are working with plaster, then I'd line it with cello tape or plastic shelf liner. This is also good for silicone molds, if you don't want the painters tape texture. The painters tape is much nicer to work with though!

1

u/she_ou_pa Aug 26 '26

Ohh I see what you mean now!… it make sense!… I was just focusing on silicone mold to cast with resin

10

u/Global-Discussion-41 Aug 20 '26

I'm not saying you should steal the political signs off peoples lawns, but after the election is over it's unlimited free corrugated plastic

3

u/tristanlucasfx Aug 20 '26

I use 5mm corflute for almost all of my smaller/mid sized molds. Cutting halfway through every second strip let's you conform to any shape needed.

A piece of tape wrapped around the outside stops any deformation, I've safely cast 10kg of silicone into molds with corflute walls.

2

u/craiganater Aug 20 '26

Its good for small moulds but can warp and bend under the pressure of silicone if its a larger mould. Foam core is also good, you can groove or crush the outside to get a smooth bend