Hi! I’m working on a gift idea. I’ve made a bunch of Lego pieces and mounted them within a Lego cube frame that measures 13cm each way. I now want to cast the whole thing in resin (blue with lighter bits). The whole thing is a play on the tesseract from the Marvel comic universe. I’m a total resin novice. What considerations should I have? Will the resin curing process melt the Lego? Is a 15cm cube going to take forever to cure / will it cure? I need information. In theory I can fill the cube with more Lego to reduce the amount of resin used. How much resin will I need? Which resin in best suited? Lots of questions!

For that thickness you will need the GlassCast 50 Clear Epoxy Casting Resin which can be cast up to 50mm per pour, so 3 pours needed for your project.

Main issues with casting lego is stopping it floating initially and bubbles. The underside of lego bricks are especially bad for trapping air bubbles as are holes and around studs on the bricks.  You will need to take special care to get all the air out.  Ideally if you have a degas chamber, then degassing will help greatly. 

The lego is not going to melt as long as you keep to the 50mm casting limits.  Each layer will take anywhere between 12-24 hours before it is cured enough for the next pour.  The final pour will need 48 hours before demoulding. 

The 13cm cube needs 2.2kg of resin to fill 100%.  Less when you take into account the volume of the bricks.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Hi Warren. Thanks for the reply / recommendation. Re the bubbles - I thinking of gluing the Lego in position with something like superglue or uni bond. I could then cast the resin with the Lego upside down - would this be reasonable way to help mitigate the trapped air?

Without degassing, it can be difficult to get the air out the brick underside. You will have to pour it in stages. Sometimes poking with a cocktail stick helps.  Pouring the resin just over the brick, then gently wafting with a heat gun can be enough to make it sink into the brick voids.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

OK thanks for the info. In your experience, if I'm colouring the resin in an attempt to make the cube look the tesseract, which pigments could best achieve that effect given the 3 stage pouring?

You can still choose any pigments you want.  Just mix the pigments into ALL the resin in one hit, then decant the resin you need from the big batch for each pour. That way each pour has the same pigments in it.  Remember to stir each time you pour off a batch to avoid settling of the pigments.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

For the Tesseract appearance, you could try either the blue from the pack of 6 Translucent Pigments, or you could look at the Neon pigments which might give you a more vivid effect. Alcohol Inks could be worth experimenting with as well because they ass an explosive burst of colour.