I got PNY cs900 to clone my system disk to. Works fine but hard but to into desktop. Holes for screws in different place to HDD. Can an SSD be screwed to a metal part inside the case Would it get too hot? I have seen people say they use insulating tape .
Get yourself a 2.5"-to-3.5" adapter, for example this: https://www.amazon.co.uk/gp/product/B07QVX8TWJ/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
That adapter seem much more complex and expensive than needed. I think it safe to assume cables are already there. Something like these brackets should work just fine. I would not use insulating tape - I'm not even sure what that is in this case. There are many types. What you can also do is use a couple inches of Velcro tape. This would leave the top of the SSD exposed to the cool air flow, and even lift the drive off the surface of the case a little to allow for some ventilation underneath. That said, a mounting bracket would be the best solution.
Nonsense. You simply slot the SSD into the internal connector and fit the adapter into the 3.5" slot. The adapter will fit all 3.5" bays that take a standard HDD, as it is exactly the same size as a HDD and its external SATA connector is in the same as position as a HDD's (so existing SATA and power cables will always fit). The ones you recommend will not work in some 3.5" bays, especially those that use railings or plastic carriers used on many Dell models, for instance. I'd rather pay £8.50 for something I know will fit than £5.00 for something that may well not.
It is not nonsense. I didn't say it was complicated. I said it was complex and expensive - and it is - compared to a simple bracket. Why pay more for an adapter that comes with an electrical connector that is not needed? That's what is nonsense.
You can check the the link in my sig to see if I might know a little about hardware. The adapters I linked to do indeed work in 3.5 inch bays - even on Dells. The spacing is the exact same as your expensive model. What you explained quite clearly makes the same point for the adapters I linked to (my bold underline added) I will debate this no longer. The OP can decide from here.