Well I certainly won't argue against safety and Felix makes an excellent point that there are less toxic ways to etch. And, those should be looked into with considerations about ventilation, disposal, etc. I'm just describing the process I ended up with because there was a time where I needed to etch HUGE numbers of boards in a very cost-effective way.
I will say, spot on about the odor/fumes produced by HP and Muriatic acid. It is very, very intense and you need ventilation, a mask, and positive air-flow to minimize your exposure. These days, I've been working off the same gallon of acid for almost 8 years (that's how infrequently I do it now) and it is substantially weakened. It still etches but there are very few offensive fumes from it. There is a "safer", less potent form of Muriatic acid you can buy and I've used it, too. I think it's more like 25-50% strength.
Point being, FeCl3 is a very good alternative to peruse. When I used that, I actually would use an old pot, heat up some water, then put the FeCl container in it for a few minutes to warm up. Then when agitating I hit it with a heat gun on low. It does speed up the etching a bit.
Towards the end of my etching days I also used a laminator to do transfers onto PNP blue. It still required an iron for some final adhesion but it did make doing full sheets a lot easier. These days I only do an occasional faceplate and a simple iron is enough to do the job.
