One of the things I got for my Taz 5 rebuild was that exact WhamBam kit that Wrathernaut mentioned and gave a link for. I paid $87 for it. I intend to put the magnetic sheet on the glass bed plate.
I wanted to mention something about the modular print bed heater. I have one that I got quite a while ago when I was planning to build a Taz 5 from scratch more or less. I collected other parts too. A few months ago I bought a used Taz 5 that I am rebuilding. I am using some of those parts for my rebuild. The modular print bed heater together with the glass bed or magnetic metal bed will sit a little bit higher in the corner mounts. That is because the corners aren’t cut on the modular print bed heater like they are on the old style heater that sticks to bottom of the glass bed. The modular print bed heater fits right on the corners and then your glass (or metal) bed will go right on top. I think that the magnetic metal bed might be better than the glass, since the magnetic field will firmly hold the two parts together. The Lulzbot Octograb (aka Magnetic Flex bed) system will set you back $265 USD ($115 for the modular heater + $150 for the magnetic bed). Those corner mounts are not standard. I created them for my eventual Taz 5 build to use with the modular system. They are taller than a standard corner mount and the cut out area is as tall as what you would have on a Taz 6 corner mount when you place the heater and bed into it. You can see the top is flush with the glass. I am not using any springs under the corner mounts. The corner mounts are flush with the glass plate. I plan on using a BLTouch or another probe for bed leveling.
Thank you all very much for your answers.
In the end I have opted for one of the solutions proposed in the thread. The idea, as was said, was to give more life to the TAZ5 without spending more than the printer is worth today. It is good but old.
To do this I have chosen to replace the glass with this:
(more less 40€) Sorry I live in Spain (Europe) but 40€ is more less 40$.
It includes the magnetic sheet plus a flexible steel plate with two sides: one for PLC and another for the rest (eg ABS).
As for the side supports, the corner doesn’t seem to be a problem, even if you print on a PLC it doesn’t get hot enough. I took advantage and mounted some spring supports to be able to adjust the bed.
For the moment, I have tried it with the ABS face and the truth is that it gives very good results.