Before you make a teleprompter you need either an Android tablet, iPad or reversible laptop etc to display the scrolling text you could use your smart phone if that is all you have but you want the text to be as big as possible. Also my version of a teleprompter is simplified as I did not need to make a dark back drop for it as my camera setup has what is called a "matte box".
However to make a simple teleprompter holder I used an off cut of a piece of 2x4, and I cut a 45 degree slot into it. This is simply to hold the glass.
I then use an off cut of 10mm ply and trim to size using the table saw. I glue and screw the 2x4 we cut flush at one end and let dry. I proceed to paint the contraption mat black and stick a piece of felt on to the base where the tablet will sit.
I use some of my spare GoPro mounts to make a mount for the tripod. I have to modify one of the cheaper parts so that I can make the mounts in versed.
I bought a really cheap picture frame... and used the glass from this. It was thin enough that the reflection ghost from the opposite side of the glass is not that noticeable... Normally you would use beam splitter glass which can be expensive but you get a much higher quality of reflection in the glass with no ghosting.
If you wanting to make something like this yourself, you will need to ensure the camera is close to the glass and blocking light. You can use material and I was going to cut the bottom half off an old t-shirt and use that.
There are many many other tutorials online and videos on youtube... that cover it all this is just showing how I made mine for my setup. ie; if I did not have a matte box on the camera I would have made it differently.
The software I use is from Google Play Store for Android, and called Teleprompter Pro at cost about $10. There are many free ones available but this is the one that met my needs.