Such maps are readily available from tourist spots, but generally do not cover older glassworks.
I have one from the 1920s/30s covering Der Bayerische Regierungsbezirk Oberpfalz. But it does not identify factories just has a symbol by those towns with glass-works. Obviously, you cannot tell if they are glassworks or refineries. That is an area rich in glassworks.
You can also get such maps from glass museums and they tend to be a little bit more useful.
Ideally, you should work form the large scale maps as these show the glasswork buildings with 'probably' great accuracy. But then even if you know where the glassworks were it can still cause confusion.
Here are maps of Perth, Scotland showing some of the glass works that have existed there.
1859 marked in Orange and also showing the location of one built in 1891 http://www.ysartglass.com/Photo/Perth1859.htm
This 1860 large scale map shows another 'Bottle works' just South of the first map http://www.ysartglass.com/Photo/JMbottleworks.htm
Fron the same 1860 map I show the Inkworks where glass was made too. http://www.ysartglass.com/Photo/JMinkworks.htm
Same map same company but just a glassworks to cope with expansion http://www.ysartglass.com/Photo/JMglassworks.htm
Then a 1913 map with all the glasworks marked http://www.ysartglass.com/Photo/Perth1913.htm
note the different position of the southern works. The 1891 works are correctly placed on this map, so the first one needs correcting.
I have yet to ascertain exactly how many glass works existed in Perth at any time.
Now, that points out some of the difficulties. I have maps, somewhere, of other areas - mostly Europe that show locations of glassworks and there is probably a wealth of material that can add to this from all the books published so far on glass.
A practical approach would be start with Ivo's book, probably the most extensive published list of glassworks in the world and against each company determine a map co-ordinate. Using this data, create an overlay for Google Earth and you then have a good starting point. Ivo book does not include refineries or decorators but they would be of interest too. The other problem will be coping with name changes and glassworks that move from one location to another.
Hopefully, this has not deterred you and you will make a start