ShortScale.org

i guess this was the thing Jimi Hendrix used in his recordings. i've never owned one, but i've used digital simulation for some time now, and i really like the sound. (i used SimulAnalog guitar suite - their amp simulations sound very accurate and also it's all for free!)

my question is... is there any modern analogue of this pedal? dunlop univibe doesn't sound right to me.
would it be very hard to DIY this one?

There are some modern analogs. The Fulltone Deja 'Vibe is probably the best (a bit pricey, though).

Cheaper alternatives are the Moen Shakey Jimi (found on eBay from Hong Kong). These sound pretty good, but have a bit of a volume drop and a cheap bypass switch. There's also the Danelectro Chicken Salad Vibrato, which is quite good and only about $30, and the Danelectro Cool Cat Vibe, which doesn't sound quite as natural but has a heavy duty case and true bypass. These cheaper ones use an LED instead of a light bulb in the LFO circuit, and therefore have a very similar but not identical sound. The Fulltone is the closest to an original without the inconsistencies and volume drop issues the Dunlop has.

Mewithoutus (forum member) is working on a totally accurate Univibe clone with his company Watson Effects. They were planning to have it available sometime in the next few months.

It's a pretty difficult pedal to clone accurately. There are variations like the Easyvibe though that are a bit easier.

Lovepedal Vibe rules. I plan to buy one soon enough.