As a modeler nearing 80, I suffer from the drawbacks of the older modeler. The vision problems I can generally take care of with the proper optics and lighting, but the loss of manipulative skills are harder to deal with. I use jigs and fixtures a lot in building. I build several genres of modeling, and several different scales. I have found no universal jig for holding either the model nor parts. So I build my own.
I started by using particle board, and with the wider availability of MDF at building supply stores I have started using that instead. I have a bandsaw in my shop so I can cut the stuff.
With the subject being talked about in several recent issues of FSM I am contemplating doing an article about tools and solutions for the older modeler, but for now I will just recommend that you consider making your own jigs for each model. I find I make anywhere from a couple to many jigs for each model. Some are to hold model or subassemblies during painting, some for drilling accurate holes, and many for holding parts in position while the glue sets. I find my fingers start trembling even trying to hold parts in position accurately even for the few seconds it takes CA to set up.
There is the three hands needed problem off holding two parts together, requiring two hands, while I apply CA accelerator with the third hand :-)