I only have two Macs. A fairly new 27 inch iMac and a 2007 2.2GHz MacBook. Both have slot load disc drives. However, I have been sent a new bit of electronics which has the instruction manual on a small 80 mm (8 cm) CD.

Is there any way I can read this on either of my Macs?

If not is there a cheap external drive around with a tray that will take it?

The mini-CD will not work in either Mac that you have now. If you insert the CD, it will be lost. I've taken a bunch of CD drives apart, just to retrieve a stuck mini-CD or mini-DVD.

An external CD drive with a tray - probably not less than $50 - http://eshop.macsales.com/item/Other%20World%20Computing/VLU2SD22X/

Have you checked at the web site for the gear that you purchased? You may find that user manual as a download.

If i were you i would buy one of the Blu-Ray Externals (http://eshop.macsales.com/shop/blu-ray) and just get the shareware Mac Blu-Ray Player (http://www.macblurayplayer.com/). I use this software right now and they have been good about keeping up the Blu-Ray copyright through free updates to the program.

How does that fit with the OP's question?
Not quite "cheap", and the OP may not need that if the manual is available for download.
There's also a good chance that the manual on the mini-CD is Windows-only.

Thanks for the suggestions. I'm looking at this Dynamode (http://www.pcworld.co.uk/gbuk/dynamode-insixt-external-slimline-usb-cd-drive-black-04877726-pdt.html) one, but the local PC World were out of stock last night. So ordered online. We'll see.

I'm expecting it to be a Windows program. Maybe the manual is text, but there's a bit of software too I believe. I would run this on the laptop under the Parallels emulator.