assembly tools...any recommendations?

[Macneil]

I've been looking at some modded seiko's and it doesn't look too difficult to assemble one...anyone here done it and can recommend th required tools?

[8Ace]

A watch repair kit from the likes of ebay will suffice at first - something like this:

https://www.ebay.co.uk/itm/600-Pcs-Watch-Repair-Ki...

This will allow you to open cases, replace crystals, remove hands change spring bars etc and it comes with a blower too which is vital if you're building your own. The last thing you need the day after finished your watch is to note a tiny speck of dust on the dial. Guess how I know this.

The spring bar tool will be rubbish, but you don't need a Bergeon (even though it is brilliant). Something like these will be fine as a starter:

https://www.ebay.co.uk/itm/Watch-Band-Spring-Bars-...

If you're building watches you need some decent hand pressers. Forget the cheap ones with a spring loaded plunger, they're abysmal. Get something like these and you have much more control. You'll need a loupe too, a 5x one is OK but 10x is better as the hands are very fiddly.

https://www.ebay.co.uk/itm/Set-3-Wristwatch-Hands-...

Lastly - get some latex gloves. a fingerprint on the dial or the underside of the crystal will ruin the final effect. Good luck.