Here's what I started with: A bunch of my nid bits box stuff, an official exocrine model, a Tyranofex model, and my own converted Exocrine of yore for inspiration...oh, and a bottle of peaty scotch :)
I first tried to mock up the beast with the original exocrine arms.
...However, the exocrine arms weren't working for me in that position, so I moved the arms forward to extend the profile of the model. I was already loving it a lot more :)
Next it was time to figure out a suitable barrel layout for lobbing massive spore mines. Fortunately, I have a massive Tyranid beastie that I started constructing back in 2011-ish, which was meant to be a Tyrannofex before that model was released. I have never finished the conversion, so I snagged the obscenely large gun barrels off him and reconfigured them to serve the Dactylis:
Next up, I had to extend the tail because the exocrine's existing tail is REAL pathetic :(
Also, I was hoping to use the tail as one further point to anchor the Dactylis when it was setting up to fire. I accomplished the extension by trimming off the end of the original tail, then making a tail shape out of aluminum foil and binding it in some very thin copper wire.
In that photo you can also see the big, bloated spore sac I created to hold the Dactylis' ammunition. In case it's not obvious, I used the termagant sacks from a Tervigon, but switched up the alignment of them to change the profile from tall to wide. They fit together pretty well in this alignment without the need for too much cutting.
Though the Exocrine is a pretty big beast, this Dactylis was going to have some much larger cannons sprouting from its back, and I really wanted it to look like this beast was powerful enough to lob its spore mines over great distances.
Thus, I wanted to give the Dactylis even more vents on its back, and expand its carapace. The perfect bit for accomplishing this was a piece of the back from a Tervigon, so I managed to wedge that in the middle of the original Exocrine back piece:
With the gun barrels, body, and arms sorted, it was time to put them all together to figure out the pose for the Dactylis. I wanted to make sure the barrels were at such an angle that they could convincingly look able to fire spore mines at targets way far away.
Sculpting Tyranid biocannons is really easy so long as you do them in the right order. Though you can sculpt it on after, I find it easier to do the ribbed vascular tissue for the barrels first. In this first image, you can also see how I've scored up the smoth plastic of the barrel to give the putty a rough surface to grip.
Next up, for the head, I wanted something kind of unique, so I chose this axe-head option, and I converted the jaw so that it didn't look like it was bellowing at the top of its lungs like most Tyranids.
Thus, I extended the armour plates on the Dactylis' head to cover its eyes. this has the added benefit of giving the enemy one fewer place for a lucky shot to punch into the creature's brain, taking it out.
I first traced the armour plates on thin cardboard to get the right size and shape, then I retraced them from the cardboard onto plasticard and cut out the shapes. I wanted the huge armour plates to curve around the Dactylis, protecting its lower limbs and clutch of spore mines at the back. To accomplish this, I took a page out of the book of Kelfrei, got out my heat gun, and used it to shape the armour.
Though I didn't get any photos of it, I accomplished this by gluing the plates on with super glue, waiting for it to dry, then drilling down through the plate, into the plastic beneath, and anchoring each one with a paper clip that I'd folded into an upside down "L" shape. Part of the L stuck into the hole, and the other part at a 90 degree angle ran along the surface of the plate. I then covered this with a bunch of greenstuff.
Finally, the Dactylis needed a second set of supporting arms to anchor it while firing. Due to the way the fore arms and arm shields had been set up, these would mostly be hidden behind the shields, so I used bits from the Tervigon to make some monstrous scything talons.
And THAT, is how you create a monstrously large Dactylis >:)
That was a pretty quick and high-level run through of the build, so if you have any questions about it, feel free to leave them in the comments section below, or send them to me on Twitter or Instagram.