Production
Once parts are finished developing, they can be turned real parts that can be mounted to the car. This can be done on the production page where you can assign mechanics to the production process.
Overview
At the top of the page, there's an overview panel that shows the following aspects of your team.
Mechanic Points
This is the number of mechanic points you have and which can be used. These may be used either for producing parts (from the Production page), increasing the Pitstop efficiency (more information further down in this article) or testing in the simulator. The last two functions are available from the Preparations page that can be found in the Session menu.
Production quality
This is taken into account in the production of parts to determine how close, in terms of ratings and weight, the produced parts will be to the ratings and weight given in the Development plan. This is determined by the Mechanic team (assigned Head and Junior Mechanics) and other factors. The lower this is, the worse parts will be when compared to the design. If your mechanics have a really low skill, it's possible that parts will differentiate in rating even when they are produced from the same plan.
Pitstop efficiency
This value is taken into account when carrying out pitstops during sessions. The higher this value is, the faster pitstops will be. Having fast pitstops can give a strategic advantage to a team by making sure that the drivers lose less time in the pits than their rivals. This value can be increased from the Preparations page.
The overview panel also shows the number of parts being produced and those finished for each part type. This is given in the form <parts in production>/<parts produced>.
Projects
Once the design has been finished in the development section, it will be available to be produced in the production section. The parts are produced using mechanic points (red). Once produced, parts can be mounted to the car on the cars page and are available in every session until it's deleted.
There's no storage limit of parts, but as every part costs money to produce it wouldn't be a good idea to produce way more than your team needs.