Been learning Sharp Dressed Man by ZZ Top recently - I'd heard it on the radio and thought I'd have a go. I had most of it down and thought I could manage a version of the slide solo using a finger. Nope.
Took a trip to a local store and bought a Stagg slide pack. This a two slide pack, one full size, one half size. They look like chrome-plated steel. Here's an Amazon picture:
Got them home and started. I'd no idea how fun these would be to use! Worked out some of the solo, spent ages just playing around with the slide.