I have 4 Zinger Wingers (minis and 1 field trailer) which we bought for the days when there is just my sister and I training. I prefer the Minis because they are easier to handle and can fit crosswise in the truck bed. They are good for hunt test training but we still prefer hand thrown birds for field trial. Are you thinking manual or remote launch (electronics)? When we are using them by ourselves we take the ATV because you have a great deal of walking to reload. With a group we leave someone at each winger to do the reloading.
There are a lot of different models with different release systems on the market. We also have some older homemade ones that were modelled after the Tangelo Tosser. I liked them because the tension on them was not a tight as Zinger Winger and you stepped on a lever to release. Unfortunately they were manual only so someone had to do the releasing. If you are going to make yours I would visit the websites of the various manufacturers and have a look at their release systems. You can also get some design ideas.