Here is screenshot of a recently updated PHP script called GearCreate2.0 which allows a user to create gears and save out the desired gear in one of several formats, such as .OBJ, .SVG and .PLT
http://cuttingedgedata.com/GearCreate/GearCreate.html
Years ago, I made a similar utility using MS Excel. In some ways, that old one was more powerful, in that it was capable of calculating tool offsets and producing g-code for cnc routers. Below is a link to that older GearCreate, which seems to work well in Excel, OpenOffice and even on a Mac using Numbers
http://cuttingedgedata.com/Scripts/GearCreate8fa.xls
To see a few of my other scripts and programs feel free to click the link below:
http://cuttingedgedata.com/me/StevePerlTk.html