yes it is scratchbuilt.
I have based it on the (poor & min detail) images of the Sekhamet which are on the net, from I believe an unreleased B5 computer game?
Added some minor detail to the top of the ship to make it more in line with the current Dilgar miniatures range as welll as adding more detail and guns to the underneath of the ship.
Model is virtually complete but needs to be painted, and I hope to put it up on the forum along with some other scratchbuilds I am working on, in about a month. Will attempt to paint it as Deathwalkers verson and may manage to paint up a "Nemesis" with Skull artwork to go with it.
I see the Sekhamet as being Battle Level, so I am also currently sketching up a couple of designs for a larger Dilgar ship based on the same type of look as the Sekhamet but taking it to higher threat levels.