Any tips for casting and making relatively heat-resistant/strong molds?

I'm trying to make an intake kit for a bike I own, and I'd like to try to cast and mold from my 3D printed prototype.

I've originally tried casting it in a flexible silicone. That worked pretty nice. And tried my hand at doing cold casting; mixing 1:1 ration of metal powder with resin+catalyst. And I was kinda surprised by how brittle and delicate the product felt after setting. Not sure how heat resistant it would have been either, but thats out of a lack of knowing.

Any tips for me? It sits directly on top of the carbs, and the carbs sit a few inches above the motor.

I think the easiest would be to cast aluminium in a plaster mould or sand mould. Did it at school several times, probably the easiest way to do a metal part. Avoid lead and stuff like that : not worth it.
However, you need a little setup for heating, preparing the sand, ... make sure to have the proper protections. Micro droplets or liquid metal can be projected and ARE harmful. Wear glasses, safety boots, heat gloves and arm protections.

So a plaster mould would hold up to the molten aluminium then? Should the plaster be coated with anything?

As far as a forge, I certainly don't need anything large or complex. These are small parts that won't require much metal. Is there a kit that comes recommended?

Straight plaster of Paris won't work. You need to use something intended for casting metal into, and no, there's no coating for plaster that will help much. I don't really recommend that people try casting high-temperature metals at home; there are too many little issues that you need to know about to avoid serious injuries (one little steam explosion that sends red-hot liquid metal everywhere can ruin your whole day...) I know there are lots of You-Tube videos that make it look easy, but a lot of those people don't really know what they're doing.

If you really want to do this yourself (rather than take it to a foundry, or ask Shapeways to make it for you in brass, which would be preferable) look into a Delft Clay kit - it's like industrial sand-casting in miniature. https://www.riogrande.com/Product/de...-system/705136 But it would be best to find someone who knows about casting to show you the ropes hands-on. Melting the metal and pouring it safely is not something you can do with tin cans on the kitchen stove.

Andrew Werby
Juxtamorph.com

Or get someone to print it in ALU!?

Shapeways now offer this service!

GBR1

Good point - that's a new process for them I hadn't heard they were offering. The other metal options are all printed in resin and cast, but the aluminum is printed directly. Here's the run-down: http://www.shapeways.com/materials/aluminum/