If you wanna print it yourself, the model is here: https://www.printables.com/model/1348194-4n-threaded-flat-head-screws-and-nuts-10-32-equiva
Design to be a drop in replacement for 10-32 screws with a much, much higher pitch. These screws are extremely easy to print, is reliable enough that it can hold some weight.
If you wanna print this yourself, you need to make sure that the screw is sideways, so if it breaks it’s no on the layer lines.
Using them in my own prints which had metal screws and they are holding quiet well.
@Fondots @Bluewing especially since the terminology is different in different dialects of English. I think what you call lag bolts might be coach bolts over here.
Lag bolts are more like a big wood screw, what you call coach bolts seem to be what we call carriage bolts