This is a basic camera slider. You can watch the video for the assembly and results. The holes on the slider body are 5 cm apart,you can attach anything you like. I've also shared the STEP files. Have fun! :)

YouTube video:https://youtu.be/eI_8c7X8S4E

Parts designed by other people that I used in this project:
Linear Bushing link: https://www.thingiverse.com/thing:2202854/files
Phone holder link: https://www.thingiverse.com/thing:2194278
Phone holder mount link: https://www.thingiverse.com/thing:6399538/files

speed controller: https://tr.aliexpress.com/item/1005006365907342.html?
dc motor: https://tr.aliexpress.com/item/1005004297630876.html?

Materials:

2x 10MM 50CM Smooth rods
4x Linear Bushings (3D printed or standard)
4x Zip ties
1x Dc motor speed controller
1x Dc motor
1x Limit switch
1x String
1xPhone or Camera for filming :)

Bolts for Slider:

1x M3 30MM bolt
2x M3 25MM bolt
8x M3 15MM bolt
2x M3 10MM bolt
13x M3 Nut
2x M3 Washer

Bolts for Phone Holder:

3x M4 20MM bolt
3x Washer
3x M4 Nut

1x M4 60MM bolt
2x M4 Nut

2x M4 20MM bolt
3x M4 Nut