Perlite & Concrete Cast Dome Build

I’m going to try building a Cast Dome oven over a Yoga Ball for my first attempt (only cause I’m pushing 70 and it looks like the easiest - also 9 stents in the heart limit what I can do)
Has anyone advise on the mixture - Can I use a cement mixer or could I use a drill and whipper to make the mix ???
I just can no longer do the vigorous hoe or shovel mixing!
Planning on using Perlite & White Portland - then covering with blanket and coating with mortar and possibly dressing it off with old brick to give it a look (if my body holds up)
Any suggestions or information will be greatly appreciated