the bigger the jump, the bigger the bang: if a large entity jumps a long way, it uses a huge amount of power and creates a bigger visual ordeal.
the transition to warp space could create a portal big enough for the entity to fit through in any direction (equivalent to 2x longest point-to-point of its bounding box), which then closes after it - but the bigger the entity, the slower the hole closes (so that the entity can be chased through warp inside its stream). the entity's speed would increase at normal acceleration speeds up to 3/4 of its top speed (if not travelling that fast already) but without using thrusters. any other inertia would be forcedly dampened, and its manoeuvring would be locked until it was fully inside the wormhole so as to stop it changing direction and colliding with the edge of the portal on the way through. the warp would not start until the entity's direction-of-flight was within 5° of aiming at the destination, and the orientation was within 10° of the destination. the portal would then calculate - from dampening inertia and accelerating towards the destination - where and when to open so that it is centred on the entity's profile (even if the entity is at an angle when going through) and is wide enough upon contact that all blocks will fit through, even though the portal is still opening. this could mean that the entity is still spinning as the damping is taking a while to stop its inertia, but the portal will still successfully consume the whole entity due to where it appeared.
the exit portal from the wormhole would work by calculating what point the entity would need to reach at maximum portal speed to be fully open when the first block of the entity reached it. when the entity reaches this point, the portal would start to open, but the entity's manoeuvring would not be changed. once the last block of the entity has exited the portal, the manoeuvring lock would release and revert back to whatever state it was before the jump.
the portal would be cancelled if the entity's movement deviated from the calculated path by more than 5%, and would start to close again. this would only be possible if another entity collided with it hard enough to throw it off course or an explosion was big enough to do the same. at this point the simulated acceleration would cease and the manoeuvring controls would be unlocked.
during entry, it should distort the view in some way, like if the whole 360 view was stretched into a flat circle at the end of the wormhole, and wraps around the entity as it exits (similar to
this). as the wormhole opens it would also do the opposite looking backwards.
the wormhole would be a separately formed region whose length is determined by the amount of power used in the jump compared to the distance being travelled; more power shortens the tunnel, but a longer distance increases it.
entities can manoeuvre inside the wormhole, but controls are locked to maximum manoeuvring speeds of the
entity that generated the wormhole.
ALL entities are pushed through at 3/4 the maximum speed of the
entity that generated the wormhole (± manoeuvring). this allows multiple entities to have a slow-motion dogfight during warp, but would not be able to reverse thrust so much that they stay in the wormhole forever - even trying to reverse at full, they would still be deposited at the destination.
if an entity gently collides with the boundary of the wormhole, it will bounce back into the middle. if it collides at-or-above the server collision damage threshold, then blocks will be broken off the entity and scattered into normal space based on where they were along the wormhole at the time of breakoff. this would destroy an entity if it could not recover its direction-of-flight quickly enough, and would scatter carnage all along the warp path. this effect could be used as a tactical advantage in battles if entities warped across the battlefield, firing dud entities from rails at the sides of the wormhole to scatter debris in front of the enemy.
as a final note, it would be cool if trying to enter a wormhole exit the wrong way would take you back along the path in the opposite direction - at the same speed - but only as long as the portal is open - as soon as it is closed, the tunnel collapses and spits the entity into the spot that it would be in at that point in time, using a different exit animation that drops it out through a wibbly-wobbly effect that is a sphere 2x the size of the entity's longest point-to-point of its bounding box (similar to
this) with some foggy, sparky effects whilst throwing the entity into a crazy spin, turning off auto-dampers, resetting shields (start recharging from 0%), and doing a random (but fairly minor) amount of damage to the entity (this animation, spin, and auto-dampers-off could also be used if implementing interdiction, but no damage to ship or shields). this would also happen to an entity that went in the correct direction after the entity that generated the wormhole, as long as the wormhole fully closed before the following entity reached the end.
in short, if an entity warps into the vicinity and a ship is losing in a fight, it might be able to dive through the portal in the hopes of losing its foes, and if they follow, they will be dropped a reasonable distance apart, as they will have entered the wormhole at a different time, but will be dropped at the same moment (and therefore further back along the line).
also, any ship/other entity that is straddling the portal border and does not fit as it closes gets cut up... this would be a special cutting where the block occupying the same space as the edge of the portal is destroyed, so if its stationary, a flat cut goes through (or as flat as can be if the entity is at an angle) but if it's moving as the portal closes, the cut is conical - as the hole gets smaller, more of the entity is left behind (any blocks behind the ones that are destroyed). the remaining section of the entity inside the portal is deposited - along with any debris - in the same manner as previously stated, but as the travel would then only be the time it takes for the portal to close from 1m wide, it would not travel far at all, but it would make for some epic destruction if anything got caught in it.