Angel's Bio mod has some buildings that require rare, single-use resources to be found on the map. An example of this are the tree seed generators. (https://www.reddit.com/r/factorio/comments/8g8che/angels_bio_processing_where_do_the_trees_for_seed/)

Having maintenance on these items is a bit painful, because you cannot find too many of them, which means you will quickly exhaust your ability to construct new buildings. Ideally this wouldn't exempt a building entirely from maintenance, but just for that ingredient and the need to replace the building entirely.

This could be done via introspection, but I think it is not so easy to determine that an ingredient is only available via mining terrain objects.

Maybe this could be part of the [eventual] mod API?

Thanks for this hint. Using rare and limited ingredients for maintenance should be avoided, thats true. But don't worry, this is something on my list:

• From the next balancing update on, repair will only require repair-packs, but in return the whole process will take considerably more time to complete. If aided with additional repair items, repair progress is significantly speed up. This will allow the player to prioritize some parts of his/her infrastructure. Also, this will make it possible to maintain you base only with repair-packs (even if that means that ~50% of your machines will be in constant state of slow repair)
• To do this, I'll add a GUI tab with all your different types of machines that need maintenance
• This tab will not only display the different items needed for maintenance and repair for each of those buildings, but also it will allow the player to choose which kind of items should be allowed to be used as repair materials. In your specific case, you'ld probably disable the use of seeds because they are to precious, even if this means that repairing those machines will take somewhat more time.

I hope this gets along with your ideas - Thank you very much for your continous and valuable feedback :)

I like this model - good idea. Thank you. How will it work with machine replacement? Will replacement go away with the update?

There will be an new way to use machine scrap beside recycling or reconditioning it.

• Recycling will only return parts of the machine, but is still the best option for simple and low cost machinery.
• Recondition is the material expensive but energy efficient way to use your (expensive) machines again.
• Additionally, there will be new "mending" recipes (not sure if this name fits), which will only need machine scrap, water, stone (or sand), mechanical spare parts, a lot of time/energy. The main advantage is, that this will allow you to get new machines without additional use of expensive materials.

Very good - thank you!

Short update:
The new repair mechanic is implemented and the new GUI is 75% done. It will also indicate the maintenance malus / repair time increase if certain items are not allowed for use as maintenance or repair material. Because there is still some work to do, the new "mending" recipes will be added in a later update.

Because it is now possible to set an individual replacement age for each machine type, I've added a new setting option: The "max operation age".
It is disabled by default, but can be enabled to determine the maximum age to which a machine type can operate. This is to prevent failure induced machine self destruction of very old machines (age >> 100%), if the player is only able to supply repair material, but no replacement. If this is enabled, a machine stops as soon as it reaches the specified age and will remain idle until replacement is provided.

Super cool, I look forward to the update. You put a lot of thought into this - good job!

It's done :)

Awesome. I will check it out tonight. Thanks!

Awesome. I will check it out tonight. Thanks!