While setting routes on categories is definitely useful, it doesn't allow products to share a category and use different routes.  I was able to set "make to order" and "buy" as defaults for new products without changing available routes on other products in the same category by adding a rule in Settings > Technical > User-defined defaults.  The trick is to look up the database id of the route(s) you want to set as default.  For my purpose, I set a rule with Name: route_ids, Model Name: product.template, and Default value: [5, 1].  Now, new products default to "make to order" and "buy" when added on the fly, but if a product is added that should not have "make to order", it can be deselected manually even if it belongs to the same category as other "make to order" products.

Hello Jaydeep, 

Could you send me you python code please ?

Regards,

activate developer mode with assets, go to the product template form and tick the buy and make to order box. in the top right corner, click the 'Bug' button and select 'set defaults' from there you can select the fields you have changed and set their current values to be the default values when you create another product.

Hi Chris Tringham,

I tried with "Automated Actions". It's working well.

Create "Automated Actions" with Trigger Condition "Based on Form Modification".