Good progress on the bench!
I’m using what I have for the top. If it doesn’t work out well I can always unbolt it and and replace.
Have you considered using sheet vinyl for bench top covering? Also check classified/craigslist for freebies and building/construction materials for cheap bench top material.
I built many portable reloading benches for friends and to save cost, I used scrap 2x4s and leftover OSB/plywood for tops and covered the ugly OSB tops with heavy reinforced vinyl sheets from Walmart craft/sewing department for waterproof "no-splinter" top. Even with thin OSB, extra 2x4 mounted flat under the OSB (where press is mounted) fastened to 2x4 frame with 16d nails and screwed to OSB top provided absolutely "no flex" reinforcement to the bench top even when resizing thicker military .308 brass.
Nice thing about using old scrap 2x4s is that they are dry and solid as rock where new green 2x4s are soft and pliable so they won't split. BTW, I built my 2'x3' bench out of new kiln dried 2x4s with every nail/screw hole pre-drilled to prevent splitting.
Here is my 2'x2' portable bench (used for pistol calibers) built from rough scrap 2x4s with scrap OSB top covered in reinforced vinyl with satin finish to hide the ugly rough OSB and as cheap temporary covering. But after almost 10 years, the top has no rip and still looks great. At the time, I had 2'x6' and 2'x8' benches in the garage (castered with HEAVY casters but I got tired of reloading in the 100F+ heat of garage and these industrial benches built to take the weight of engine blocks were given to friends who needed heavy benches). The 2'x2' bench was meant to be temporary until I got the portable 2'x3' bench finished but since it worked so well, I ended up keeping it.
Vinyl covering was pulled tight and stapled to the bottom of 2x4 frame
Here's a 2'x4' bench I built for a friend who needed rifle brass sorting station (Yellow bin unit from Harbor Freight which can be removed if needed). OSB top reinforced with double 2x4s where LCT was mounted eliminated bench top flex and covered with plain vinyl to reduce cost. After over 10 years of use, the vinyl covering is still in great shape.
Hole for middle vertical 2x4 was cut into the top, vinyl fabric folded into the hole and stapled then vertical 2x4 was inserted through the hole and fastened to the 2x4 frame of bench top.
For my 2'x3' bench, I wanted durability and waterproof finish top so I went with 11 layer hardwood veneered plywood and 3 coats of polyurethane (Front of plywood was covered with hardwood strip). The bench top finish has withstood almost 10 years of hard use with spillage of various solvents/oils and easy clean up is done with a piece of paper towel.
As to the bottom shelf, I did the same but added a 1/2 deep middle shelf so I could reach the stuff in the back of bottom shelf (pegboard goes to the bottom of middle shelf so things don't fall out).
One bench is enough FOR NOW. I still need to get the shop in order.
Even for those with full anchored reloading benches in the garage/reloading room, imagine the convenience of rolling a 2'x2'/2'x3' bench into the livingroom or patio to resize brass, clean/swage primer pocket, hand/bench prime etc. while watching TV or chatting with wife and sipping iced tea ... a man's house is his castle, right?
Another benefit of having castered portable benches is I can move them out of the way when I am not reloading/working at the bench. At the previous house, 2'x3' bench even rolled right into the walk-in closet as 2' width will go through any doorway/hallway (and why bench was shortened to 3' from 4' original length). Currently 2'x2' bench is stored in the corner of the reloading room but rolled out when I need to use another single stage/Pro 1000. The 2'x3' bench is usually stored pushed against the wall for bench work and tipped out about a foot to reload at the press.
I am currently designing another portable bench to mount Dillon 650 with case feeder and the new Lee Pro 4000 for full-time sit down reloading. Unlike previous benches which were built for both standing/sitting operations, this one will be customized for easy reach operations while sitting for my retirement years. I will post pictures once I get started with the bench build.