Customising your Mac’s desktop using OS X’s built-in tools doesn’t take long, and if you were thinking you could make radical changes you’ll be left disappointed. Thankfully there are many tweaking and customisation tools out there, but none go as far as CrystalClear Interface 2.7.4.

This tool allows you to radically revamp the look and feel of your desktop, with a new menu bar and re-skinned windows, applications and dialogue boxes, complete with transparency. It’s incredibly simple to use if you just want to set it and forget it, but also boasts all the fine-tuning tools more advanced users crave.

CrystalClear Interface (CCI) is quite resource-hungry – you’ll need a 2GHz dual-core processor (ideally an Intel Core i5 or better), plus at least 2GB RAM. CCI 2.7.4 also promises to work with all versions of Snow Leopard, and the latest builds of OS X Lion (10.7.3 and 10.7.4) too.

Ten fully formed themes are provided with CCI.

Once installed, reboot your Mac and your new desktop awaits. The default skin – Dark Light – immediately makes a difference, and the new menu bar should be your first port of call after opening a Finder window to preview the new theme.

You’ll find CCI has added a button to the left of the Help menu – clicking this reveals all the tweaks and shortcuts you need. Start by selecting Preferences and you’ll be able to try one of the other nine themes with a single click.

Go further by exploring the Frames, Alpha (transparency settings), Colors, Graphics and Extras tabs for all the additional options you need – up to eight new menu bar settings, four button designs, multiple frame designs and all the fine-tuning you could ask for.

Most changes are instant, but some do require you logging off and back on again, so don’t experiment with too many applications open. You’ll also notice that certain apps aren’t affected by CCI – they either use their own interface or are known to be incompatible, so are disabled. Other apps that refuse to work with the new regime can be similarly excluded from CCI’s skinning via its System Preferences pane.

Give your Mac's desktop a radical makeover with CrystalClear Interface.

The asking price of $15 doesn’t seem excessive, and the trial version is fully functional for 15 days, so gives you enough time to have a play and decide if it’s for you.

It’s worth noting that because CrystalClear Interface performs various hacks behind the scenes that it’s not going to work with subsequent Lion updates or the forthcoming Mountain Lion without a further update, with no guarantees any might be forthcoming if things change drastically in the OS. With that in mind, have a play, but consider waiting to see how the land lies if you plan to upgrade to Mountain Lion on its release.

CrystalClear Interface 2.7.4 is a free trial download for suitably powerful Macs running OS X 10.6.x (Snow Leopard) or 10.7.3/10.7.4 (Lion) only.