My 16mm film scanner

The size should help you narrow if it is 5W or 10W. Once that is established, probably start with an LED driver for the same power.

Either (5W or 10W) will require heat dissipation (a good heat sink).
Light is a journey, not a destination! Below a bit of my journey.

For initial test, a ping pong ball and a good LED strip is an easy prototype.

PS. The selection of a good Illuminant, the LED, is probably the most consequential decision on the quality of the scan, followed by the system chosen for making the light even (diffuser, sphere, etc.)