Liquid plastic resin for plumbing application

I'm guessing you are talking about making a data logger to monitor fermentation temps, mash temps, etc. Your question is quite vague and you need to clarify it to get better answers. What temps are you talking about, environmental conditions, etc. What parts are going to contact the beer/wort? A drawing would help.

I've used weatherproof electrical boxes to house electronics. Several websites, like http://www.buyfittingsonline.com/ sell stainless fittings that you can use for tubing or enclosing temp probes. I use high temp food grade silicone tubing in my rig along with stainless steel.

For sealing purposes or molding parts to hold electronics, you can use Sugru (https://sugru.com/about), which should handle most of your needs. It works like putty, cures overnight, handles high and low temps, and bonds pretty well to most surfaces. It remains somewhat flexible (like silicone) which may be good or bad based on your specific use. Be careful in that Sugru has a short shelf life (must use in 6 months) and is not certified food-safe, although its properties seem to indicate that it should be. Their website says:

Once cured, sugru is inert, but people can be allergic to anything, so we have to tell you to be careful. sugru isn't certified as food safe yet, but we're working on it. For now, please resist the urge to eat it.