New member & DRO

Just found this group - great info.

I don't want to re-invent the wheel or plough through 17k+ postings
so can anyone help with guidance on building a DRO for my lathe and
mill?

Here in the UK encoders I have seen cost an arm & a leg. Has anyone
experimnted with using a mouse (with suitable gearing) as an encoder
and driven by a timing belt?

Do I use an old computer or build a LED display?

Hope someone can help - keep up the good work.