Gflex has a thickened version that might work well, though you might have to use a piece of fiberglass to give it structure.  I don't think many plastic welds would hold well if it took any impact. 
Gflex has this going for it:
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not that I would advise taking a chainsaw to a new boat, but still...

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  ( just search for "epoxy stick" on the Home Depot site - that brings up 3 or 4 varieties)


this would likely work well, and not cost a lot.   two part epoxy putty stick - this one (if the link works) is Loctite brand - I've used similar product on my royalex boat, to sorta make a sorta skidplate and lug a few of the deeper dings.  easy to work, and since its a putty, would be easy to plug up the holes if you have something for a backing to keep it in place till it cures.  the stuff I used, I don't think I even cleaned the hull, just plastered it on - and its still there after maybe 5 years of use.

Home depot has other similar products that are designed to work with plastic - "plumber's epoxy" stuff that isn't affected by water


the only downside to the epoxy putty, at least the one I used, is it dries white - so wouldn't look very pretty, maybe

most likely, any two part epoxy would work, but liquid versions would be harder to use to fill a hole, I'd think.

plastic welding ? maybe, but that depends on how thick the materail is - only experience I've had was wleding cracks in snowmobile gas tanks - using a soldering iron, and plastic coffee can lids - works, but you needed to have enough material thickness to melt a groove at the crack that could take the melted plastic filler.

G-Flex epoxy is another product designed for use on plastic and works for boats - not sure how much it costs and what quantities you can buy in (i.e. small amounts) - its also a liquid, so harder to use as a filler in a hole.

I'd think, even contact cement would do - just put a plastic - plate over both sides of the hole

maybe this could help?:
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My first suggestion would be a schedule (waste) PVC end cap as material for a plug and then epoxy or maybe glass and epoxy. BUT I don't think epoxy would adhere to either. Maybe worth a try though.

Is there a 1" threaded pvc plug you could screw in and sand down? Never know. Maybe PVC glue would melt and harden?

Interesting problem.

I recently picked up two Pelican cases really cheap. The only catch was that the prior user had cut a 1" hole in the side of each. They were using them to store batteries, so they had a sealed connection coming out of the side.

I've removed the connection, so now I just have a clean 1" hole. Any ideas for the best way to patch/repair this?

I reached out to Pelican, thinking that if I could get some more material, then I could plastic weld a plug in place. They couldn't provide me with anything, so I am open to suggestions.