Hi @Rock201314,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
You might like to have a look at this Sliding barn door project from @Jwyatt as inspiration for your barn door.
They have used Pine lining boards, 89x19mm Pine DAR and 140x19mm Pine DAR to create their door.
I'd suggest these are perfect materials to make a barn door that are easy to work with and relatively cheap.
The process of constructing the door would involve gluing and clamping the pine lining boards together, before cutting them square.
Once the pine lining panel has been created, you would glue and nail the DAR pieces to the pine lining panel using a finish nailer and wood glue to achieve the finished barn door look.
You would then fill the nails with a suitable filler depending on the finish you choose to use and then coat with either paint, oil or lacquer depending on the finish you'd like to achieve.
You might also like to check out Handmade barn doors and Workshop barn doors for some further inspiration and guidance.
Let me know what you think and if you needed further guidance, please don't hesitate to reach out.
Jacob
