I have a project where I need to make a build out of lego's its gonna be a large build so I have to glue it together.
Can you guys give me suggestions on what kind of glue to use. Id like the glue to melt the plastic together to make the bond super permanent. I think a quick work time would be best but I would like to hear all your suggestions!
Lego is made from ABS plastic. As such the best method is the same used for 3D prints, making your own.
A craft glue will bond two brinks but won't "weld" them or melt the plactic together for that you'll need to mix shredded ABS with Acetone to create a paste. The paste can then be used to weld the briks together, however it relys on evaporation for the glue to set and can take up to 12 hours.
With my ABS 3D prints I use a mix of ABS acetone paste and craft glue, this speeds up the dry time and work time of the mix.
As lego should hold its shape without glue drying time shouldn't be an issue but if need be you can always clamp pieces together until the glue is dry.
I might suggest Same Stuff plastic welder.
Solvent based glues such as dichloromethane also known as plastic weald in the UK work well. If it's a small construction super glue will work but it can be brittle and not so good for large models. The easiest glue to get would be the glue for plastic model kits as it like the dichloromethane will melt the bricks together.
Dichloromethane would be my choice as it's the same consistency as water and once you have a layer of bricks in place you just brush it on with a paintbrush or an eye dropper. Capillary action will draw it between the bricks and bond them together.