There is a tunnel inside the wood where it strecthed across the terrarium. I was hoping the spider would create it's webbing inside. Here is the side view of the enclosure. The spider is only 1" and i am currently observing it's webbing behavior, although it may change as it grows or after molt...IME, they want to be touched on all sides by something to feel secure. It needn't necessarily be a burrow; web tubes, other M. balfouri, a hollow or any skinny space will work. I have one who insists on a burrow under a piece of wood contrasted with another who weaved a web retreat amongst leaves at the highest point. My enclosure concept required some revision based on this, otherwise the spider would climb to the highest corner & stuff itself close to the sides & remained there for days. I separated them out & placed them in separate enclosures with different design concepts to observe their behavior. I'm relatively certain I have a little better idea to get the result I want, but I won't rehouse for quite some time at this point. What I built previously has been relegated to one of my Chromatopelma cyaneopubescens who's quite a bit larger.
I would stuff that piece of wood with some substrate with a hidey hole started between the the substrate & the piece of wood. It will give it a starter skinny space & you'll get to observe some excavation. You could potentially add some coconut fiber & long fiber sphagnum to the sand/excavator clay to lighten it up for digging. Those who are provided a burrow are unlikely to engage in active webbing outside the burrow for some time.
If you want interesting webs you'll need to provide anchor points that are not outside of the reach of the spider, that is when their spinnerets drop web at one point the next point needs to be within leg's reach. You could provide the majority of these along the sides with a dead space in the front to prevent webbing there. A gap between the side of the enclosure & the anchor points (say, dense foilage) will cause a web tube to be woven there. So, for example, you could take another stick, glue leaves upright in a plane then position it so the leaves lean against the side & it creates a "tunnel" along the edge of the tank. This will likely end up webbed.
Hope that made sense!