O-Aust Kits was established in 1999 as a medium to make available to other O gauge railway modellers the kits that the owner had developed to provide the necessary rollingstock for his own O Gauge New South Wales prototype layout

The first "kit" was a NSWGR WHX wheat hopper which evolved as the result of a requirement for a block grain train. It was more a collection of aids to assist the scratch builder rather than a kit in the true sense of the word. Other kits then followed, including the MRC, S, BHG, MLV, UME, BCW, CW and ACM.

Recognising the need for a diesel locomotive, a project to produce a NSWGR 48 class DEL was undertaken. Recognising the complexity of the task Bergs Hobbies were approached to assist with the project. The kit was finally launched in 2005.

In 2005, the owner felt that the business had "reached the crossroads" and it was time to either return to being a modeller or to upgrade to a sustainable business. The latter course of action was chosen.

New kits are continuing to be developed, including prototypes other than New South Wales. Upgrades to the existing range are also occurring where it is feasible. The full range of kits, with the exception of the WHX will continue to be generally available for the foreseeable future

Century Models was established by Graham Holland in the mid 1990s to provide locomotives and rollingstock to O Gauge modellers of the New South Wales prototype in the scale 7mm to 1 foot.

In February 2006 O-Aust Kits purchased the rights to the patterns and future sales of the Century Models range of New South Wales prototype steam locomotives. The range, which includes the Z19 and D50 will continue to be offered under the Century Models name.