Observations of active eruptions can provide insights into spatter and scoria cone formation. As Kilauea’s 2018 East Rift eruption developed and the outflow of lava localized at Fissure 8, a spatter cone began to grow. As apparent very early in the cone development, the Fissure 8 eruption produced a horseshoe shaped cone similar in plan view to many scoria & spatter cones observed worldwide. Observed processes that impact cone shape include directional winds, a strong effusion component, and sloped topography. No evidence for destructive processes that might remove part of the cone (such as the gap where the lava flow emanates) was evident in publicly available images and videos. Instead, the gap (or breach) in the cone clearly coincides with the exit location of the lava. Most likely any scoria falling in this region is carried away (or melted) by the lava flow. From a morphometric perspective, these observations suggest that so-called breached cones may simply be cones with a strong effusion component to the eruption. That is, the “missing” section of the cone was never there rather than being destroyed later. Testing this hypothesis can be approached in at least two ways: One approach would be to relate morphometric characteristics to estimates of the relative proportions of effusion (lava) and explosion (spatter, scoria, and ash) from field studies. The accuracy of such studies is likely dependent on the age, local climate, and overall field relationships. Alternatively, 3D modeling of the combined explosive and effusive processes can drive increased understanding of how these complexities of cone shapes develop. Directional delivery (due to winds) of ballistic scoria, effusive processes (which can remove scoria on landing), and sloped topography provide potential mechanisms for creating variations in cone shape, particularly in plan view. This study extends a 2D ballistic model to 3D to consider such processes as wind impact, directional fountaining, and the removal of material by lava flows.